Skip to main content

Full text of "Bulletin of the British Museum (Natural History), Geology"

See other formats 


PA ou 


‘ 
j 


BO in git 
Legis Ae? 


tier 
a 


‘(ie aa 
oP j 


THE: rr 20 VE ace tt 
ig Bee, as: ; 
Bear FURAL— 
+ i SR a) ooh rtheaenaahrr va pice aihvieedih” 
a ag 

' a ie Ec dy 


has a 


S74 \ 


3 it ae ¥) 


BULLETIN OF 
THE BRITISH MUSEUM 
(NATURAL HISTORY) 


GEOLOGY 
VOL, 21 
1972-1973 


TRUSTEES OF 
THE BRITISH MUSEUM (NATURAL HISTORY) 
LONDON: 1974 


DATES OF PUBLICATION 
No. 
No. 
No. 
No. 
No. 
No. 


30 June 
29 December 
I4 June 
. 31 October 
1 November 
29 December 


PUR wDH 


PRINTED IN GREAT BRITAIN 
BY JOHN WRIGHT & SONS LIMITED, AT 


OF DHE PARTS 


1972 
1972 
1973 
1972 
1972 
1972 


THE STONEBRIDGE PRESS, BRISTOL BS45NU 


i 


CONTENTS 


GEOLOGY VOLUME 21 


PAGE 
The shell structure of Chonetacean brachiopods and their ancestors. 
C. H. C. BRUNTON I 


Postcanine occlusion in Cynodonts and Tritylodontids. 
A. W. CROMPTON 27 


The Lower Miocene ruminants of Gebel Zelten, Libya. 
W. R. HAMILTON 73 


The affinities of Halcyornis from the Lower Eocene. 
C. J. O. Harrison & C. A. WALKER I51 


Dinoflagellate cysts and Acritarchs from the Kimmeridgian (Upper 
Jurassic) of England, Scotland, and France. 

G. U. Girmez & W. A. S. SARJEANT 7 
[See also Bull. Br. Mus. nat. Hist. (Geol.), 18 (7) 1970 : 231-331] 
Mid-Tertiary Cytherettinae of north-west Europe. M. C. KEEN 259 


Index to Volume 21 351 


IETACEAN BRACHIOPODS 


: { (NATURAL HISTORY) _ 
: Vol. 21 No. E 


ee 


eel a 
uel at es 
01 


eh 


We 


aie SHELL STRUCTURE OF CHONETACEAN 
BRACHIOPODS AND THEIR ANCESTORS 


BY 


HOWARD BRUNTON 


Pp. 1-26; 9 Plates, 8 Text-figures 


BULLETIN OF 
THE BRITISH MUSEUM (NATURAL HISTORY) 
GEOLOGY Vol. 21 No. 1 
LONDON : 1972 


THE BULLETIN OF THE BRITISH MUSEUM 
(NATURAL HISTORY), instituted im 1949, ts 
issued in five series corresponding to the Departments 
of the Museum, and an Historical series. 

Parts will appear at irregular intervals as they become 
veady. Volumes will contain about three or four 
hundred pages, and will not necessarily be completed 
within one calendar year. 

In 1965 a separate supplementary series of longer 
papers was instituted, numbered serially for each 
Department. 

This paper is Vol. 21, No. 1 of the Geological 
(Palaeontological) series. The abbreviated titles of 
periodicals cited follow those of the World List of 
Scientific Periodicals. 


World List abbreviation 
Bull. Br. Mus. nat. Hist. (Geol.). 


© Trustees of the British Museum (Natural History), 1972 


TRUSTEES OF 
THE BRITISH MUSEUM (NATURAL HISTORY) 


Issued 30 June, 1972 Price £2-00 


BULLETIN OF 
THE BRITISH MUSEUM (NATURAL HISTORY) 
GEOLOGY err Vol. 21 No. 1 


\ Wi 


ADDENDA ET CORRIGENDA 


p. 6, caption to Fig. 2 
The inhalant current arrow should have a flight on its tail, the exhalant current 
arrow no flight. 


p. 7, paragraph 3, line I 
For “‘teleolae’’ read “‘taleolae’’. 


p. 9, caption to Fig. 3B, line 3 
An arrow without a flight should be inserted before “‘exhalant current’’. 


p. 24 
For “GRAnrT, R. E. (in press)” read “GRANT, R. E. 1972. The lophophore and 
feeding mechanism of the Productina (Brachiopoda). J. Paleont., Tulsa, 46: 


213-48, pls 1-9”. 


P. 25 
The reference after WiLiiams, A. 1968, should be WiLLiAMs, A. 1969. The 
book was published by the University of Wales Press not “‘aloes’’. The reference 
following should be WiLLiAMs, A. 1970. 


P. 25 
Under “Locality details of figured specimens”, the second name should read 
“Leptelloidea leptelloides”’ not ‘‘Leptelloides leptelloides’’. 


by ae 
: , 
- 2 
aa 
AY 
oe 
& - 
pat 
\ 
i 


tf ce 7 
ets Orgs)... oe Brio tA 


_ ‘ 

o ae ¥ we 

‘+ eh YD ' c 

i : a6 

ta _ 

; . ae 
— - i 

ad 


eu 
7 
—— a 
A _— 
' 
® =, 
& 
fiona) a 
7 i 


pi 


|, 


i 


mae SHELL STRUCTURE OF CHONETACEAN 
BRACHIOPODS AND THEIR ANCESTORS 


By C. H. C. BRUNTON 


CONTENTS 
Page 
I. INTRODUCTION 5 : : : ¢ : 9 ° : 3 
Il. MorpHoLocy . : c : : . ; ; : 4 
Ill. ANCESTRAL STOCKS : : : : : 2 i : 9 
IV. PLECTAMBONITACEA 6 : : : : 6 5 : 10 
V. SHELL STRUCTURE . : E : : : . : ¢ 13 
Plectambonitacea é é : 5 : : . 13 
Chonetacea. ° : é : : : é 5 16 
VI. DISCUSSION AND CONCLUSIONS . ¢ : 4 : “ . 20 
VII. ACKNOWLEDGEMENTS : : ; : . : . c 23 
VIII. REFERENCES . : : : : . ° F . : 24 
SYNOPSIS 


The criterion of shell microstructure has been added to general morphological considerations 
in this study of possible ancestors for the Chonetacea. The results support Havlicek’s 
suggestion that the sub-family Aegiromeninae was the plectambonitacean stock from 
which the first chonetacean evolved in the late Ordovician. Ordovician to Permian 
chonetaceans have been studied and the observed changes in their shell structure are discussed. 
Functional morphological interpretations are presented and consideration is given to the 
significance of spines in these brachiopods. 


I. INTRODUCTION 


Dur1nG the past ten years or so there have been several notable publications on the 
Chonetacea. The origin and phylogeny of the group has always been problematical, 
for, as Muir-Wood wrote in 1962, ‘More research requires to be done . . . if the 
relationship of these very numerous and wide-spread forms is to be established.’ 
She briefly discussed chonetacean origin indicating that she favoured the Plectam- 
bonitacea as ancestors, but reminded readers of Paeckelmann’s suggestion (1930) 
that the chonetids were derived from a strophomenid stock. 

More recently Boucot & Harper (1968) have revised Silurian and Lower Devonian 
Chonetacea, but restricted themselves to phylogeny within the group and made 
no comment upon ancestry. However, Havli¢ek (1967) while discussing the 
evolution of the Sowerbyellidae ‘. . . assumes Chonetoidea to be incontestibly the 
direct precursor of the superfamily Chonetacea...’. Havliéek derives Chonetoidea 
from an Aegivomena stock whilst Eochonetes is derived from the Sowerbyella stock. 
In his view, therefore, Eochonetes is not in the group ancestral to the chonetaceans 
as I had implied in 1968. 

Thanks to the stimulus provided by the work of Williams, especially his shell 
structure study of 1968 which formulated a framework for future research, we are 
now in a better position to apply detailed examinations of shell microstructure to 


4 SHELE STRUCTURE 


the problems of phylogeny in a meaningful fashion. Williams interpreted the shell 
microstructure of the Chonetidina, Productidina and Strophomenacea as being 
fundamentally the same, (i.e. entirely laminar) while that of the Plectambonitacea 
differs in retaining a fibrous secondary layer. In his phylogenetic chart Williams 
(1968) derived the chonetids, productids and oldhaminids from the Strophomenacea, 
which in turn, along with the Davidsoniacea and ‘probably the triplesiidines’ he 
derived from the Plectambonitacea by a process of neoteny: the laminar shell of 
the strophomenides being homologized with the laminar primary layer of the 
plectambonitaceans. 

We are left, therefore, with the need to investigate the possibilities of chonetids 
being derived either from plectambonitaceans involving a change of shell structure, 
or from the strophomenaceans, with which they appear to have a common shell 
structure. 

Clearly, in any such study the more factors investigated the better. I believe the 
microstructure of the brachiopod shell to be so intimately bound up with the 
metabolism of the living organism as to be of profound importance systematically ; 
nevertheless, it is vitally important to consider closely the gross morphology of the 
valves so as not to suggest evolutionary relationships involving highly improbable 
morphological changes. The purpose of this study is the detailed investigation of 
the chonetacean shell microstructure, together with that of their possible ancestors, 
in the hope of resolving the early phylogeny of this group, the evolution of which 
took place during Upper Ordovician times. 

I retain here the view expressed in 1968 that the Chonetacea should be classified 
more closely to Productacea than, for instance, to the Strophomenacea. The 
removal of the Cadomellacea from Muir-Wood’s suborder Chonetidina (Cowen & 
Rudwick 1966) leaves only the Chonetacea, and, at present, I am in favour of leaving 
the situation fluid to the extent of retaining the Chonetacea as a superfamily within 
the Strophomenida and not using the term Chonetidina. The Productidina usefully 
unites several superfamilies which have reasonably established morphological 
characteristics in common. The Strophomenida as a whole is an order within 
which there is room for phylogenetic reappraisals, e.g. the removal of Thecospira 
and Cadomella (Brunton & MacKinnon, in press), and introduction of the Triplesiacea 
and Thecideacea, problems upon which several palaeontologists are engaged and 
have already commented (Cowen & Rudwick 1966, Williams 1968, Rudwick 1968, 
Wright 1970, Mr. D. McKinnon personal communication January 1971). 


II. MORPHOLOGY 


The most recent and complete description of chonetaceans is that of Muir-Wood 
(1962). Several aspects of their morphology have been discussed (Brunton 1968) 
but further work now necessitates some revision. 

The main point of departure from the views expressed in 1968 concerns the 
possible reconstruction of the lophophore (1968, text-fig. 50). At that time the 
traditional idea of a spirolophe for chonetaceans was followed. However, more 
recent studies on this group, productaceans, strophalosiaceans and thecideaceans 


CHONETACEAN BRACHIOPODS 5 


leads to the opinion that the lophophore in these fossil groups consisted of a 
schizolophe or variously lobed forms of a ptycholophe. In the sense of Williams & 
Rowell (¢w Williams et al 1965 : H37-8) it is a lobed trocholophe because the 
lophophore is believed to have had only a single series of filaments, as in Recent 
Thecidellina, rather than the more complex double filaments characteristic of most 
other Recent lophophores from the schizolophous to plectolophous stages. Rudwick 
(1968) reminds us that the terminology employed to describe lophophores was 
based originally upon the arrangement of the brachial axis without consideration 
for the number of filament rows. Thus whilst phylogenetically there is logic in 
Williams and Rowell’s terminology (1965, H38), it is less confusing to retain the 
previously existing definitions qualified, where necessary, to indicate if the filament 
series is double or single. Believing that the thecideaceans may be remnants of the 
Strophomenida, derived from a productidinid stock not far removed from Cooperina 
Termier, Termier & Pajaud 1967 (but see Cooper & Grant I969), it is logical to 
interpret the chonetacean lophophore as having been only a single row of filaments 
(Text-fig. 1). In his study of the Triassic brachiopods Thecospiva and Bactrynium 


Fic. 1. Diagrammatic dorsal valve interior of a chonetacean showing, on the left, general 
morphology and, on the right, the inferred anatomy and suggested water currents 
associated with the lophophore, a. — anderidium; a.ad. — anterior adductor muscle scar; 
ad.v. — adductor muscle, ventral attachment area; b.p. — brachial platform; b.w. — 
inner epithelium of the body wall separating the brachial cavity from the visceral 
cavity. The epithelium of the visceral cavity has been cut ventro-medianly to expose 
the muscles; did. — diductor muscle; did.v. — ventral attachment area of the diductor 
muscle; m. — mouth; m.e. — mantle epithelium; m.s. — median septum; n. — possible 
position of the nephrostome in the body wall, excreting into the posterior exhalant 
current; p.ad. — posterior adductor muscle scar; s. —socket; s.r. —socket ridge ;3-> inhalant 
and — exhalant feeding/respiratory water currents. 


6 SHELL STRUCTURE 


Rudwick (1968) discussed their affinities with the Thecideacea and the general 
phylogeny of that superfamily. He accepted the Termiers’ & Pajaud’s (1967) 
assignment of the Permian genus Cooperina to the Thecideacea, so that it became 
the earliest representative of the superfamily, which he considered as derived from 
a Lower Permian or even earlier davidsoniacean. Study of Cooperina shows that 
Cooper & Grant (1969) are correct in placing the genus in the Strophalosiacea and it 
seems that the morphological evidence presented by Rudwick for a derivation from 
the Davidsoniacea is better met by the Strophalosiacea, a group believed to have 
diversified widely and to have given rise to both the Richthofeniacea and 
Lyttoniacea. Rudwick (1968, 1970) related the Lyttoniacea and Thecideacea to 
the Davidsoniacea. 

While preparing this paper I was privileged to be shown the script of a paper by 
Grant (in press) in which he describes a calcified ‘ptycholophous brachiophore’ in 
Permian Productidina (ptycholophous here used as by Grant in the morphological 
sense of being several lobed). The interpretation of this structure supports the 
contention that the brachial ridges of Productidina do indeed mark the positions 
to which the lophophore was attached in the living animal and that the 
‘ptycholophous’ (or multilobed trocholophous) lophophore described by Grant 
evolved as a specialization from the more generalized schizolophe or simple 
ptycholophe characteristic of many Strophomenida. 

A study of particularly well preserved Pennsylvanian and Permian chonetacean 
interiors in the collections of the National Museum of Natural History, Smithsonian 
Institution, Washington, shows that in some rugosochonetids and species of Dyoros 
the antero-median tuberculation of the brachial ridges merges into the anterior end 
of the median septum. In some thickened (? old) specimens of Dyorvos the anterior 
end of the median septum is winged laterally in such a way as almost to bridge the 
gap between it and the brachial ridges (Text-fig. 2). The exaggerated development 
of tubercules and prolonged deposition of secondary shell in the regions of the brachial 


P br. ae 
Aas 
ici may Aa 


5mm 


Fic. 2. Anterior view of Dyorvos sp. (Chonetacea) dorsal valve from the Permian of Texas 
illustrating the highly tuberculate brachial ridges and anteriorly winged median 
septum. The inferred position of the lophophore and feeding water currents are added 
on the right. > inhalant current; 3+ exhalant current; b.p. — brachial platform; b.r. 
brachial ridge, m.s. — median septum. 


CHONETACEAN BRACHIOPODS 7 


ridges and median septum probably resulted from the stresses imposed by the 
lophophore upon the secretory mantle epithelium in these areas. It may have 
been simply the weight of the lophophore hanging from the dorsal valve that 
induced this additional shell secretion in those specimens living in a position with 
their dorsal valves uppermost. 

The chonetacean lophophore is envisaged as having been suspended from the 
dorsal inner epithelium with the postero-median mouth segment attached to the 
body wall between and probably ventral to its support by the anterior tips of the 
anderidia (= lateral septa of Muir-Wood 1962). The strong tuberculation of the 
brachial ridges probably reflects the strong attachment of the mantle to the shell 
where it supports the lophophore (Text-fig. 3). Antero-medianly the generative 
tips of the lophophore probably recurved posteriorly onto the median septum 
(Text-fig. 1); however, it is impossible to say whether they remained separated by 
the septum or united in the median plane as in living Megathiris. 

The relationship between pseudopunctae and teleolae requires clarification. In 
the brachiopod volume of the Treatise (1965 : H420) Muir-Wood incorrectly 
redefined the term taleolae, specifically as applied to chonetids, saying that they had 
a ‘central cavity’. In observing many taleolae under the scanning electron 
microscope a central cavity has never been observed. It may be that the impression 
of such a structure resulted from optical effects or that the cavities were those of rib 
apertures. 

Taleolae, as defined by Williams (1956), are rods of calcite in the axial position of 
many pseudopunctae (Pl. 1 figs 1, 2). Taleolae are found neither in all pseudo- 
punctae nor necessarily forming the core to the complete pseudopunctum in which 
they occur. When absent the shell layers or fibres can be traced into the centre of 
the structure, which is composed of inwardly and commonly anteriorly directed 
conical flexures producing tubercules on the inner surfaces of the valves (PI. I, fig. 4). 
This structure contrasts with the outward flexures of shell fabric surrounding 
endopunctae (Brunton 1969, fig. 11, 1971; pl. 11, figs 8, 10). The pseudopunctae 
of upper Palaeozoic chonetaceans have taleolae while those of geologically older 
specimens are without, or with only weakly developed taleolae. Baker (1970) 
describes Moorellina specimens within which the pseudopunctae differ in character; 
those of the dorsal valve have cores of primary shell resembling taleolae, whilst those 
of the ventral valve are without and composed entirely of radially disposed bundles 
of secondary fibres. 

In 1968 the author’s text-figure 45 indicated that he interpreted the sub-median 
ridges in the ventral valves of some chonetids as being the traces of mantle canals. 
It is now believed that in some narrow-bodied species with thickened shell these 
ridges developed in the regions bordering the ventral edge of the dorsal median 
septum. In such specimens the brachial cavity of the closed shell would have been 
divided almost completely into two chambers. The significance of this is not clear 
and the relationship of these ridges to mantle canal traces is in doubt; the effect, 
however, is similar to that of mantle canals, viz. the pressure of a structure onto the 
internal epithelial surface inhibiting shell deposition with increased shell thickening 
on either side. 


8 SHELL STRUCTURE 


a.ad. 


p.ad. 


Fic. 3A. Ventro-lateral perspective view of the dorsal valve interior of Dyovos sp. from 
the Permian of Texas illustrating the surface morphology. 
a. — anderidia; a.ad. — anterior adductor scar; b.p. — brachial platform; b.r. — brachial 
ridge; c.p. — cardinal process; dm.f. — dorso-median fold; m.s. — median septum (here 


strongly tuberculate) ; p.ad. — posterior adductor scar; p.m. — posterior margin of valve; 
s. — socket. 


CHONETACEAN BRACHIOPODS 9 


If one ignores the Daviesiellidae, in particular Daviesiella and Airtonia, and 
Chonostrophia (which may not be a chonetacean) the Chonetacea are morphologically 
conservative from their origins in the Upper Ordovician to the topmost Permian. 
Normally they share a gently concavo-convex profile, multicostellate ribbing, low 
interareas set at a wide angle from each other and several pairs of more or less 
posteriorly directed hollow spines on the posterior margin of the ventral valve. 
Teeth, sockets and socket ridges are developed, and in the dorsal valve the adductor 
scars commonly are divided by a ridge (anderidia). The cardinal process is low, 
internally bilobed in early forms but tending to become knob-like and commonly 
trifid externally; the median septum is only high anteriorly and developed late in 
ontogeny. The pseudopunctate shell manifests itself internally by tubercules. At 
least in early stages of ontogeny several genera were attached to the substrate by a 
thin apical pedicle protected by a shelly sheath. 


Til. ANCESTRAL STOCKS 


At first sight certain strophomenaceans seem suitable as ancestors to the 
Chonetacea; general shape and size of some stropheodontids seem correct, as are 
features such as the dorsal valve protegulal node and development of a pedicle 
sheath on such genera as Pholidostrophia. Williams’ 1968 investigations indicated 
that the shell structure is comparable in both groups, 1.e., essentially laminar. 
However, it is shown below that the shell structures differ and the above character- 
istics are common to the Strophomenida. 

Previous morphological studies have shown that many features are shared by the 
Plectambonitacea and Chonetacea with the result that several palaeontologists (e.g. 
Chao 1928, Sarycheva & Sokolskaya 1959, Muir-Wood 1962, Havlicek 1967) have 
thought these superfamilies to be phylogenetically related. 

Strophomenacea, Plectambonitacea and Chonetacea obviously share strophomenid 
characteristics, but whilst doing so certain features of the Chonetacea tend to be 
more akin to those of the Plectambonitacea, especially the Sowerbyellidae, than to 
the Strophomenacea. Thus the Sowerbyellidae and Chonetacea share similar shell 
profiles and outlines and do not include the same elaboration of shell shapes met 


Fic. 3B. Inferred principal anatomy added to the above specimen (in red) and possible 
ciliary induced water-current through the lophophore (in blue). 3+ Inhalant current; 
exhalant current; ad. — adductor muscle, divided dorsally by anderidium; b.w. — body 
wall with left side removed to expose visceral cavity; did. — diductor muscle; f.r.l. — 
filaments of right lophophore lobe; g.t. — generative tip of lophophore; 1.1.1. — left lobe 
of lophophore; m.l. — mouth (median) segment of lophophore, cut on left to expose 
muscle bases; r.1.1. — right lobe of lophophore; v.a. — left visceral region; v.v.c. — position 
of the interior of the ventral valve when the shell was closed; v.v.o. — inferred relative 
position of the ventral valve when the shell was open by about 20°. N.B. This 
reconstruction is not intended to imply a ventral movement of the ventral valve when 
the shell opened. Other than a portion of the body wall, epithelial layers, such as the 
mantles, are not depicted and it should be remembered that epithelia would have 
covered all the internal shell surfaces illustrated. 


10 SIENA IEAL, Sb ee OCC 7G (Ol 1 


within the Strophomenacea. Similarly with external ornamentation, save that 
accentuated costae common to several sowerbyellid genera are only hinted at in the 
oldest chonetacean genus, Stvophochonetes. 

Early and mid-Ordovician Plectambonitacea are more varied in shell shape and it 
seems that the Strophomenacea inherited this tendency to variety. By upper 
Ordovican times shell shape was more stable in Plectambonitacea and from such a 
stock the Chonetacea inherited their conservative outline and profile. 

Within the dorsal valves of sowerbyellids are paired ridges lateral to the mid-line 
or median septum, which is low or absent posteriorly leaving a cavity at the base of 
the cardinal process; a cavity interpreted as that of the brephic valve. These 
features are more common to the chonetaceans than to strophomenaceans. In 
Plectambonitacea the ridges (‘inner’ and ‘outer side septa’ and ‘bema’ of Cocks 
1970) may be homologized with the anderidia, accessory septa and brachial ridges 
of chonetaceans. The pit at the base of the cardinal process is the alveolus of 
chonetaceans. 

Whilst some Strophomenacea share some of these features, as well as denticulate 
hinge lines, their general combination is more in keeping with Sowerbyellidae and 
Chonetacea. Furthermore, some mid- and upper Ordovician Sowerbyellidae, e.g. 
Eochonetes, Chonetoidea, possibly Sentolunia, have hollow canals in the ventral valve 
posterior margin which are closely comparable to the spine canals of chonetaceans. 
Havlicek (1967 : 38) suggested that these canals may have accommodated hold-fasts 
used to attach these plectambonitaceans to seaweed. 

On looking at mid- to upper Ordovician faunas for possible chonetacean ancestors 
it seems that the morphological requirements may best be met by the Sowerbyellidae. 


IV. PLECTAMBONITACEA 


Since this study was started Cocks has published on Silurian Plectambonitacea 
(1970). His paper contains useful and interesting discussion on functional 
morphology, but not all his suggested reconstructions of the musculature and feeding 
mechanisms are accepted here. These operations have important implications upon 
the way in which the plectambonitacean/chonetacean shells are envisaged as having 
been organized. Whilst agreeing to the possibility of the shells being able to snap 
shut as a defence mechanism and possibly also as a repositioning mechanism, it is 
difficult to envisage a brachiopod habitually feeding by pumping water through its 
brachial cavity by means of a flapping valve system such as proposed by Rudwick 
(1961) for Richthofenacea and invoked by Cocks. A ciliary induced water current 
seems to be a well tried, stable and energy conserving system widely used in 
invertebrates and invariably used in extant brachiopods. By whatever means a 
water current is produced its function is to provide for respiration and feeding. 
Evidence suggests that a lophophore is required for these purposes, even allowing 
for the possibility of feeding on dissolved nutrients as proposed by McCammon 
(1969) and it seems likely that the plectambonitaceans, even the structurally 
specialized Eoplectodonta, retained a lophophore capable of a normal ciliary beat. 

It may be unwise to compare a living genus so widely separated from the 


CHONETACEAN BRACHIOPODS Il 


Plectambonitacea taxonomically, but the dorsal internal morphology of Megathiris 
has, what are believed to be, analogous structures. In Megathiris the quadrilobed 
ptycholophe, with a single series of filaments, is supported by a calcareous loop 
partially fused to three ridge-like pillars which are prominent anteriorly. The loop, 
and thus the lophophore, is a few millimetres behind the anterior faces of these 
ridges (see Treatise 1965, H 836 for fig.). The lophophore does not project pos- 
teriorly along these ridges to the extent that might be supposed from Atkins’ figure 
6 (1960, —her figure 7 gives a clearer impression of the true situation) which is 
reproduced in the Treatise (Williams et al 1965, fig. 41). The body wall, behind 
which the muscles and viscera are situated, extends antero-dorsally between these 
ridges as a dissected plane at approximately 45° to the commissural plane and 
following the postero-dorsal side of the loop. In this way the anteriorly exaggerated 
median septum and pair of ridge-like pillars lift the lophophore from the dorsal valve 
floor allowing the antero-median extension of the body cavity, including dorsal 
adductor muscles. It is thought that the plectambonitacean morphology, exempli- 
fied by Eoplectodonta, achieved similar results. 

The socket ridges, of Williams, or clavicular plates, of Cocks (1970) are considered 
to have functioned as postero-lateral supports to the body wall in the region of the 
mouth segment of the lophophore, much as were the opinions of Kozlowski (1929) 
and Opik (1933), (As the principal points of pivot in these shells occurred at the 
posteromedian surfaces of these structures the term socket ridge is favoured). In 
this respect Eoplectodonta displays a feature common to many of the articulate 
brachiopods, that of a close relationship between articulation and support of the 
body wall in the region of the lophophore. 

The plectambonitacean lophophore probably followed the lateral edges of the 
bema (Cocks), or lophophore platform (Williams), so that a variously modified 
ptycholophe, in which the generative zone (or zones) recurved postero-medianly, 
was suspended from the dorsal mantle. Assuming a ciliary induced water current 
from the brachial lip across the filamentous area of the lophophore, a circulation 
may have been achieved in which water entered ventrally, perhaps particularly 
medianly, and passed out dorsally, close to the dorsal valve and especially laterally 
(Text-fig. 4). There seems little good reason why many of the later plectambonita- 
ceans, those that had reduced their teeth, could not have had a wide gape while 
feeding. A wide gape might be advanced as the reason for very large, anteriorly 
extended, dorsal adductor muscle scars (Text-fig. 5), rather as is the situation in 
Megathiris today, which opens to about 45° or Thecidellina opening more than 60°. 
Whether or not the dorsal adductor scars of Eoplectodonta covered the bema, as 
suggested by Cocks (1970), it seems clear that these areas and those between the two 
pairs of septa on the dorsal valve, accommodated body tissues and that the lophop- 
hore was elevated on these septa. However, as in Megathiris, the lophophore 
probably did not follow the septal crests because in heavily thickened shells the 
septa may touch the interior of the ventral valve when the shell is closed, leaving 
little or no space for the brachial axis. 

The morphology of the geologically older (Ordovician) plectambonitaceans is 
indicative of a schizolophe and perhaps only in geologically younger members of 


12 SHELL STRUCTURE 


the Sowerbyellidae did the lophophore evolve into a quadrilobed structure. 

In various Ordovician species of Anoptambomites and Bimuria there is muscle 
scar evidence for the dorsal adductors being restricted posteriorly, in a more 
traditional position, and these scars are divided by raised areas which may be 
homologized with Cocks’ ‘outer side septa’ and possibly with the anderidia of 
chonetaceans. 

It is believed that the Sowerbyellidae, particularly Eoplectodonta and Plectodonta, 
were specialized plectambonitaceans which nevertheless retained essentially normal 
systems of feeding. Their ‘cousins’, the Aegiromeninae remained more generalized 
and are morphologically more suitable to have provided the stock from which 
chonetaceans evolved. 

The Aegiromeninae tend to be small-sized shells, commonly about Io mm. wide, 
gently concavo-convex with shorter interareas and more regular ribbing than the 
Sowerbyellinae. Socket ridges are reduced and the dorsal median septum does not 
extend posteriorly to the cardinal process but appears to be flanked by the adductor 


Fic. 4. Stylized illustration, based on Bimuria siphonata Cooper, from the mid-Ordovician 
of Pratt Ferry, Alabama, showing the internal dorsal valve morphology on the left with 
the inferred lophophore and main muscles on the right (red). The blue arrows indicate 
the main circulation of water through the lophophore, and this is further illustrated by 
the small diagram of an open shell, viewed posteriorly, on the right. (The dorsal valve 
is uppermost and water enters from the front) a.ad. — anterior adductor scar; ad.v. — 
ventral attachment area of adductor muscle; b.p. — brachial platform; b.r. — brachial 
ridge; did. — diductor muscle; m. — mouth; p.ad. — posterior adductor scar; s.r. — socket 
ridge. 


CHONETACEAN BRACHIOPODS 13 


muscle scars and variously placed elongate tubercules which may have assisted in 
the support of the lophophore. There is a complete lack of the strong dorsal internal 
ridging typical of the Sowerbyellinae and Leptellinidae and this morphology is 
entirely suitable as being ancestral to the sparsely featured early chonetacean dorsal 
interiors. 


Woe GSISNZILIL, Gi wires 


Plectambonitacea 


Morphologically the Sowerbyellinae form a closely knit subfamily. The shell 
structure of the genera investigated (Sowerbyella, Viruella, Eoplectodonta, Thaer- 
odonta, Plectodonta and Eochonetes) supports this unity. In these genera the 
secondary shell layer is standard in that the fibres show an internal mosaic (PI. 1, 
fig. 4) and the typical cross-sectional stacking (PI. 2, figs 1, 2) familiar within Recent 
terebratulids and rhynchonellids. The outer primary layer appears to be more 
variable, thin and commonly poorly preserved, and may be differentiated simply as 
a layer of much smaller ‘fibres’ (Pl. 2; figs 3,6). These outer elements do not seem 
to show the brick-like cross-section or lateral fusion that would be expected in a 
lamellose fabric. Taleolae are not strongly developed in the pseudopunctae of these 
shells. 


Itc. 5. Median longitudinal section of Eoplectodonta showing the inferred adductor and 
diductor muscles as they might have been when the shell was shut (5A) and open with a 
gape of 45° (5B). The ventral attachment area of the adductor muscle (coarse 
stippling) is close to the median plane whilst the dorsal attachment area is between the 
submedian septum (or inner side septum), here omitted, and the outer side septum, seen 
beyond the muscle. 


14 SHEN ICAL, Sab IR WG Ae RIS, 


An unexpected structure shows in the shell of particularly well preserved 
Eoplectodonta transversalis (Dalman) specimens from the uppermost Llandovery of 
Gotland. The pseudopunctate secondary layer also has small endopuncta-like 
canals of about 3 ym diameter surrounded by small outward deflections of the fibres 
producing a cone-in-cone structure (Pl. 3, figs 2, 3) contrasting with that of the 
pseudopunctae. It is not yet known to what extent these small endopuncta-like 
structures pervade the shell and it has only been possible to trace any one of them 
over a distance of about 80um through the secondary layer. They run subparallel 
to the pseudopunctae and it seems, therefore, that they were controlled by anteriorly 
migrating points of outer epithelium as distinct from the fixed positions of caeca 
around which the epithelium moved. 

The subfamily Aegiromeninae seems rather more varied in its shell structure, 
as judged by evidence from Aegivomena, Aegivia and Sericoidea. Within this 
subfamily the shell structure differs from other Sowerbyellidae. 

In Aegivomena aquila (Barrande), from the middle Ordovician of Czechoslovakia, 
the secondary shell is not entirely composed of standard fibres. Whilst retaining a 
well-separated, independent appearance, as if having been encased within organic 
sheaths during life, the typical fibre cross-sectional shape has almost been lost; only 
in rare instances (Pl. 3, fig. 5) can such fibres be distinguished and these tend to be 
towards the outer surfaces of the valves i.e. they were formed at early stages in the 
growth of the shell. Normally the fibres are about 14um wide and elliptical in 
cross-section, their edges overlapping adjacent fibres to various extents (PI. 3, fig. 5). 
The shell fabric is strongly pseudopunctate and these normally have taleolae (Pl. 4, 
figs I, 2). Towards the external surface of valves the fibres are of a slightly smaller 
dimensions and tend to be thinner. A strongly differentiated primary layer has not 
been recognized, if indeed it ever existed, but these smaller external fibres may 
indicate a gradation from a thin laminar primary layer to the fibrous secondary 
layer. 

Aegiria grayi (Davidson) from the Wenlock Shales of Dudley, England, is sparsely 
pseudopunctate and the fibres of the secondary layer retain a rather more standard 
appearance (PI. 4, fig. 3). In these respects the species is somewhat more akin to the 
Sowerbyellinae, but the general morphology would not warrant a change to this 
subfamily. Primary shell was not distinguished in the material studied. 

In Sericoidea restricta (Hadding) from the Caradoc of Girvan, Scotland, the 
sparsely pseudopunctate secondary layer shows virtually no sign of retaining 
standard fibres. The ‘fibre’ units within the shell appear to be well separated, as if 
formed in the standard manner within organic sheaths, and are of comparable 
dimensions (25-30 um wide and 3-4 um thick). Orientation of the ‘fibres’ remains ~ 
subparallel from layer to layer (Pl. 4, fig. 4, Pl. 5, fig. 1), thus retaining the 
organization of the standard regime rather than the marked alteration in the 
orientation of blades in adjacent sheets typical of many Strophomenida (see 
Armstrong 1969). Again, a well-differentiated primary layer has not been 
discovered unequivocally. Recrystallization is most common at the shell surfaces 
and pressure solution of the enclosing sediments interferes with the external shell 
fabrics. However, over certain areas of the valve’s exterior a layer of small laminae 


CHONETACEAN BRACHIOPODS 15 


can be seen (Pl. 5, fig. 2). These are only 3-4 um wide, appear to grade within one 
or two layers into the full-sized fibres, and probably constitute a remnant primary 
layer. 

We have, therefore, within the Aegiromeninae a differentiation of at least the 
secondary shell layer away from the standard parallel fibrous fabric typical of 
geologically older plectambonitaceans (Ajhtiella, Inversella, Toquimia, Leptestia, 
Leptelloidea, and Bilobia), genera studied to demonstrate the standard nature of the 
early plectambonitaceans (PI. 5, figs. 3, 4) and which continued on within the 
Sowerbyellinae. Ptychoglyptus and Xenambonites have not been studied. 

It is Havli¢ek’s opinion (1969 : 38) that the sub-family Aegiromeninae is the group 
from which chonetaceans evolved. Further, he assumed ‘Chonetoidea to be incontest- 
ably the direct precursor of the superfamily Chonetacea in which canals extended 
posteriorly into long hollow spines’. Unfortunately it has been impossible to find 
Chonetoidea specimens suitably preserved for the study of their shell, but 
morphological considerations support Havli¢ek’s opinion that Chonetoidea evolved 
from a Sericoidea-like ancestor. 

It is necessary, therefore, to test this suggested phylogeny against the shell 
structure of the oldest known chonetaceans. The oldest undoubted species is 
Chonetes (Eochonetes) primigenius Twenhofel (1914) from Anticosti Island, Canada. 
Twenhofel recorded the species from four formations, the Charleton (= Vauréal) 
and Ellis Bay Formations of Richmond (high Ordovician) age, and the Gun River 
and Jupiter River Formations of Lower Silurian age. The holotype was figured 
from the Gun River Formation and a ventral valve exterior figured from the 
Charleton (Vauréal) Formation. It is still generally agreed that the Ellis Bay 
Formation is uppermost Ordovician in age. Dr. O. A. Dixon has been kind enough 
to send rock samples with this species from Mile 5, Juniper River and Mile 2 
47 Mile Road, Anticosti, from the Ellis Bay Formation. Amongst these are several 
examples of dorsal valve interiors (Pl. 5, figs 5-8), figured for the first time here, and 
the shell substance is reasonably well preserved in the ventral valves. The species 
was assigned by Muir-Wood (1962) to her new genus Stvophochonetes. Boucot & 
Harper (1968) called into question the validity of both Stvophochonetes and Proto- 
chonetes of Muir-Wood (1963). A study of Lindstrém’s specimens of Stvophochonetes 
cingulatus (in the BM(NH) collections and used by Muir-Wood in defining the genus) 
and of Protochonetes ludloviensis Muir-Wood, type species of that genus, together 
with specimens of P. striatellus (Dalman) from the Wenlock of Gotland, a species 
very close to /udloviensis, convinces me of the separate identity of the two genera. 
In the author’s experience unabraded S. cingulatus and S. primigenius specimens 
always have a ventral median accentuated rib. The outline is relatively less wide 
than in Protochonetes ludloviensis or P. striatellus, and whilst spines may be 
abundant on Stvophochonetes (up to at least seven pairs) they extend more or less 
perpendicularly from the valve margin. Those of Protochonetes extend postero- 
laterally. A divided ventral median septum in Strophochonetes has never been 
observed. 

It is perhaps significant that a collection, as yet undescribed, made by Dr. Cocks 
from the low Wenlock Knockgardner Beds of Girvan, Scotland, includes many 


16 SHELE STRUCTURE 


chonetacean specimens which appear to show characteristics intermediate between 
those of the types of Strophochonetes and Protochonetes. The specimens are small, 
approximately Io mm. wide, and in outline resemble Protochonetes; the ribbing is 
even but the ventral median septum is ill defined posteriorly. Spines seem to be 
variably disposed, some nearly perpendicular, others at an angle to the hinge line. 


Chonetacea 


The shell of S. primigenius is characterized by its parallel to subparallel arrange- 
ment of fibre-like elements (PI. 6, fig. 1, 2) which both overlap adjacent fibres 
laterally and, in other parts of the shell, abut to their neighbouring fibres with a 
more or less perpendicular plane of separation. Whilst the packing of these fibres 
is tight, they retain a discreteness and do not show signs of having fused laterally 
with adjacent units, as is the situation in the bladed and sheet fabrics of Armstrong 
(1969) or truly laminar fabrics of Williams (1968, 1970). These lath-like fibres are 
6 to 10 ym wide and of variable thickness, but commonly between 2 and 4 ym 
thick. Pseudopunctae are sparsely developed in ventral valves (Pl. 6, fig. 1), but 
judging from the dorsal valve internal tuberculation pseudopunctae are more 
common in this valve. 

A clearly differentiated primary layer has not been recognized, but towards the 
exterior of the valves the fibres have the appearance of Williams’ ‘crested lamellae’ 
(1968 Pl. 21, figs 2, 4). In Strophochonetes this structure may result from slight 
recrystalization of the outermost shell layers. 

The seemingly separate nature of the shell ‘fibres’ and lack of sheet fabrics leads 
to the conclusion that the shell was laid down essentially in the standard way as 
proposed by Williams (1956, 1968), that is by individual outer epithelial cells 
secreting the calcite for individual fibres which were separated from one another by 
organic sheaths. 

Other chonetacean records from Ordovician rocks are unsatisfactory. Study of 
the specimens recently referred to by Lister, Cocks & Rushton (1970) from upper 
Ordovician rocks of the Bobbing Bore, Kent indicates that they probably are 
chonetaceans. However, preservation is poor and the shell material is lacking or 
altered. Reed (1944) described a new species, Chonetes (Eochonetes) celtica, from the 
Upper Ordovician Balclatchie Beds of Ayrshire, Scotland, which was assigned to 
Strophochonetes by Muir-Wood (1962). Neither spines nor spine bases can be seen 
on the holotype in the Hunterian Museum, Glasgow and the acutely angular 
relationship of the interareas is much more suggestive of a plectambonitacean than a 
chonetacean. 

From Middle Llandovery rocks of Newlands, Girvan, Scotland Dr. Cocks has 
found two ventral valves of a Strophochonetes species showing spines, but no shell is 
preserved. By mid-Silurian times chonetaceans were becoming more abundant, 
but their main diversification did not take place until the Upper Palaeozoic during 
which first the Plectambonitacea and then the Strophomenacea died out. 

In addition to Strophochonetes the following chonetaceans have been studied for 
shell structure: Protochonetes striatellus (Dalman) from the mid Silurian of Gotland, 


CHONETACEAN BRACHIOPODS 17 


from where also comes a small chonetacean species, possibly Eoplicanoplia Boucot 
& Harper 1968; P. ludloviensis Muir-Wood from Upper Ludlow rocks of Eastnor, 
Hertfordshire; Dawsonelloides canadensis (Billings) from Lower Devonian rocks of 
Gaspé, Quebec; Retichonetes vicinus (Castelnau) from mid-Devonian Arkona shale of 
Ontario; Rugosochonetes species from Lower Carboniferous strata of County 
Fermanagh, N. Ireland; Mississippian of Oklahoma, and basal Namurian of 
Northumberland; Neochonetes from the Permian of Texas, USA, and specimens from 
the Permian of Russia. 

In general the shell fabric of these later chonetaceans supports that seen in S. 
primigenius. Pseudopunctation, including well differentiated taleolae, became 
more strongly developed by the lower Devonian (PI. 7, figs. 1, 3) and continued 
within the stock. The greater part of the shell thickness retained a lath-like 
fibrous nature (PI. 7, figs 1, 2), although each ‘fibre’ was only from 2-4 ym wide and 
up to about Ium thick, until the early Devonian when there are clear signs of lateral 
fusion of ‘fibres’ (Pl. 7, fig. 3) into units 8-10 ym wide. In lower Carboniferous 
specimens, such as R. si/leest Brunton, while lath-like units are readily distinguishable 
throughout much of the shell their orientation from layer to layer is variable (PI. 7, 
fig. 4) and towards external surfaces sheets of blades are developed (PI. 8, figs 1, 2) 
into what approaches a true cross-bladed fabric (PI. 8, fig. 3). 

Thus it seems that a trend away from the typical fibrous secondary shell of many 
Ordovician Plectambonitacea can be traced through members of the Aegiromeninae 
into the earliest known chonetaceans of the Lower Palaeozoic and on into the Upper 
Palaeozoic when chonetaceans were at their most abundant and diverse (Text-fig. 
6). It seems, therefore, that within the Chonetacea the laminar shell fabric, like 
that of the Strophomenida other than the Plectambonitacea, developed indepen- 
dently from that in the Strophomenacea which, in Williams’ (1970) view, arose from 
a Cambro-Ordovician plectambonitacean-like ancestor derived from the nisusiid 
Billingsellacea (Text-fig. 7). This change in shell structure involved a reduction 
in the size of fibres indicating a reduction in the size of the secretory outer 
epithelial cells. This trend continued in the early chonetaceans, along with a loss in 
regularity and consistency in growth direction of the fibres at any one time or at 
different times during ontogeny. This may have resulted from the increased 
development of pseudopunctz to which small areas of specialized epithelium became 
fixed. In this way local areas of epithelium may have been retarded in their 
general anterior growth, so distorting the uniformity of calcite secretion in adjacent 
areas. Furthermore, an increasingly mobile epithelium, in terms of periodic 
retraction from the valve edges, would have resulted in the likelihood of renewed 
forward growth taking place in slightly altered directions and consequently the 
non-alignment of new fibres. 

If the development of all laminar shell is as inferred by Williams (1968) for 
Juresamia then a continued reduction in epithelial cell size did not continue. In 
Willams’ view a single epithelial cell (implied by his text-fig. 25 as being about 
I2 um wide) secreted several blades, each to some extent separated by impersistent 
proteinous strands and abutting laterally to form more or less continuous sheets. 
The alternative is for each blade to have been secreted from single epithelial cells, in 


18 SHELL STRUCTURE 


the case of Devonian and Carboniferous chonetaceans between 2 and 5 um wide, 
which progressively ceased to produce the protein sheets which separate normal 
fibres. But in whatever way laminar shell was deposited it is clear that the 
epithelium was unusually mobile by modern standards (Brunton 1969), and that the 
proteinous strands and old cell boundaries were ruptured at times of mantle 
regression. At such times the regressing epithelial cells probably laid down a 
proteinous sheet continuous with the periostracum. During transgressive renewed 


were PLECTAMBONITACEA CHONETACEA STROPHALOSIACEA|PRODUCTACEA STROPHOMENACEA 


[PERMIAN | 


J 
Intermediate 
Laminar 


Standard Cross-bladed 


Laminar 


Craspedalosia 


CHONETIDAE 
ANOPLIIDAE 
EMESIS 
Helaspis ©: : 


Devonalosia 
Spinulicosta 


Transitional == 
Fibrous = 


Leptaenisca 


Plectodonta 


Ludlow 


Protochonetes 


Wenlock 


\ 


Z 
< 
a 
=) 
= 
7) 


Aegiria 


Llandovery 


, 


il 


. Strophochonetes 


Ashgill 


Thaerodonta 
‘YEochonetes 


Caradoc 


Aegiromenas 


Llandeilo 


ORDOVICIAN 


Virvella 


Llanvirn 
Arenig 
Sowerbyellinae Aegiromeninae 


. 4 ’ ‘ 5 , 
chonetids productids 
SOWERBYELLIDAE 


Fic. 6. Inferred phylogenetic relationships between those genera of the Plectambonitacea 
and Chonetacea in which shell microstructure has been studied. Those taxa in which 
the name is horizontal have not been studied in detail. Principal features of the 
secondary layer shell fabric are differentiated and labelled in italic script. Five productid 
genera are included to indicate the results of preliminary investigations on their shell 
structure and relationships. It is suggested that the plectambonitacean to chonetacean 
changes in shell structure may have continued and given rise to the productids. 
Leptaenisca, commonly cited as ancestral to the Productacea, would seem not to have a 
typically strophomenacean shell of cross-bladed laminae. 


CHONETACEAN BRACHIOPODS 19 


calcite deposition these proteinous layers would have become entombed within the 
shell fabric and consequently separated one skeletal sheet from another so 
accentuating the lamination typical of this type of brachiopod shell fabric. 
Preliminary results from the investigation of mid-Devonian productacean and 
strophalosiacean shell microstructures shows them to be composed of semi-parallel 
lath-like units 2-3 wm wide with little development of laminar sheets (PI. 8, fig. 4, 
Pl. 9, fig. 1), whilst Carboniferous and Permian productaceans have typical cross- 
bladed fabrics (Pl. 9, figs 2-4). Such fabrics may be explained as a continuation of 
the evolutionary trend outlined above, but further study is in progress on this 


Recent t 


Cal 


r aad 
ee xe (x Thecospira & Cadomella ——. Koninckinacea, Spiriferida ) SINCE 


<< 


Jurassic S 


Ja x 
Triassic : a) 
| Lp eR er 
= LYTTONIACEA cooperininid 
Permian RICHTHOFENIACEA | | 
| : 
Merah caeicennee eee a 4 


DAVIDSONIACEA 


STROPHALOSIACEA 


Carboniferous SRODUETAGEA 


CHONETACEA | 
Devonian 
STROPHOMENACEA bee Se I, ce | 
Silurian 


7 ae 
een Le | | 


BILLINGSELLACEA 


PLECTAMBONITACEA 


Cambrian 


Fic. 7. Speculative phylogeny of certain superfamilies of the Strophomenida, together 
with their ancestral stock, the Billingsellacea. The strophalosiacean Cooperina-like 
group may be close to the stock from which the Thecideacea arose. Pseudopunctation 
was developed within the Davidsoniacea and at the start of the Plectambonitacea. 
Endopunctation developed in the Thecideacea, possibly early in the Jurassic. 
(*Thecospiva and Cadomella have been placed in the Davidsoniacea and Chonetacea 
respectively. It is thought likely that they belong to the spiriferide Koninckinacea). 


20 SHELE STRUCLIURE 


question and the more traditional derivation of these stocks, via Leptaenisca, from 
the Strophomenacea may yet prove possible. Study of two imperfectly preserved 
specimens from the Haragan Shale of Oklahoma shows that the shell fabric of 
Leptaenisca is not truly laminar. The genus can not, therefore, be excluded from 
possible productidine ancestral stocks by reason of its shell alone. The shell of 
Permian strophalosiaceans appear to have retained a less laminar shell than 
productaceans. 


VI. DISCUSSION AND CONCLUSIONS 


This study, based upon shell microstructure, supports Havli¢ek’s conclusions, 
based upon morphology and stratigraphy, that the family Chonetacea was derived 
from aegiromeninid Plectambonitacea. 

Ordovician plectambonitaceans have a shell structure with small ‘fibres’ (possibly 
equivalent to the ‘laminae’ of Williams 1968) about 6 wm wide in the outer layer, 
which grade rapidly into a normal parallel-fibrous shell fabric similar to that of 
Recent brachiopods. This gradational change may simply be a reflection of the 
increase in size of epithelial cells away from the mantle edges; a possibility which 
cannot be tested without studying well preserved and undamaged shell margins. 
Within the mid-Ordovician to Silurian aegiromeninid Plectambonitacea a progressive 
change occurred which links the shell structure of this subfamily to that of the 
earliest known chonetaceans in the uppermost Ordovician. 

Like some aegiromeninids, the lower Palaeozoic chonetaceans have a shell 
composed of small lath-like fibres which retain their individuality, in contrast to the 
sheet structures that began to develop in Upper Palaeozoic specimens. 

The internal morphology of aegiromeninids, particularly that of the dorsal valve, 
is simpler than that of most other plectambonitaceans. Within the subfamily 
various morphological features were ‘tried’, some of which may be homologous to 
chonetacean characteristics, and Havlitek (1967) suggested that some genera 
altered their way of life from benthonic to epiplanktonic, being attached to floating 
algae. Thus it was a group undergoing much evolutionary change. 

The socket ridges of Sowerbyellinae extend antero-laterally and probably assisted 
in the support of the body wall. In the Aegiromeninae socket ridges are commonly 
reduced, whilst in the Chonetacea they functioned only as socket bounding ridges 
and the role of body-wall support was filled by the anderidia. The anderidia 
probably developed from the outer side septa of the Sowerbyellinae and the low 
ridges dividing the dorsal adductor muscle scars of, for example, Aegivomena. An 
anteriorly prominent dorsal median septum is common to Aegiromeninae and 
Chonetacea and in both taxa it is believed to have been involved in the support of a 
simple schizolophe, more or less fused to the dorsal mantle. From the 
Sowerbyellinae, through the Aegiromeninae and into the Chonetacea there is a 
reduction in the skeletal support for the teeth. Dental plates are reduced and all 


CHONETACEAN BRACHIOPODS 21 


but lost in Sericoidea, Sentolunia and Chonetoidea and are lacking in the Chonetacea. 
In the ventral interareas of the last two genera Havlicek (1967) has recorded fine 
canals penetrating the shell substance, as in contemporaneous Eochonetes, and these 
structures are essentially the same as the canals leading from the valve interior into 
the spines of chonetaceans. All that is required is for the plectambonitacean 
epithelial evaginations, responsible for the canals, to have retained generative buds 
at their tips so as to have grown posteriorly beyond the posterior margin. Being 
generative, in the same way as the rest of the mantle margins, implies the sequential 
secretion of a protective periostracum followed by mineral deposition around the 
epithelial cells to form a hollow spine. It is rather as if the epithelial cells of an 
endopunctum retained a generative tip so that growth, restricted to that local area, 
continued more or less perpendicular to the valve surface. (This is not to say that 
I believe in a direct relationship between endopunctae and spines.) 

The weakly concavo-convex profile, the outline and external ornamentation of 
Sentolumia and Chonetoidea are in accord with the morphology of the first 
chonetaceans, Stvophochonetes, and it may be that the strong ventral median rib 
characteristic of this genus (Pl. 6, figs. 3, 4) is a remnant feature of the Plectam- 
bonitacea. In contrast to Boucot & Harper (1968) the present study indicates that 
Protochonetes evolved from Strophochonetes. Shell structure studies on the 
Anopliidae suggest that their origin was in common with other chonetaceans and 
that this family evolved in the lower to mid-Silurian by morphological 
differentiation. 

In considering the distribution of ancestral stocks and general evolution of the 
chonetaceans it should be remembered that the present wide geographical 
separation between the European Chonetoidea-like stock and North American 
Strophochonetes would have been less in Upper Ordovician times, if current theories 
of continental drift and the degree of crustal shortening in the North Atlantic region 
during the Caledonian orogeny are accepted. In discussing Ordovician faunal 
provinces Williams (1969) suggested a Caradocian palaeogeography in which 
oceanic currents would have distributed marine organisms (other factors permitting) 
in the European and North American provinces. Within the Ashgill of Bohemia, 
Havlicek (1967) and Havlicek & Vanék (1966) record several aegiromeninid species 
morphologically close to the chonetacean ancestor, but no chonetaceans. In the 
Richmond Series of Anticosti Island, Canada, Twenhofel (1914) only recorded 
Plectambonites sericeus (presumably Sowerbyella) with Chonetes primigenius. Thus, 
unless more recent faunal work on Anticosti proves the presence of Aegiromeninae 
in rocks older than those from which the first Strvophochonetes are recorded it seems 
this was not the area in which the evolutionary change took place. Both Aegiro- 
meninae and Chonetacea are found in Girvan, Ayrshire, but the Chonetacea postdate 
those at Anticosti. It seems possible, therefore, that the evolutionary change took 
place in the Upper Ordovician within the southern region of Williams’ palaeogeo- 
graphical model. 

Using Williams’ (1969) model it is suggested that some Bohemian Aegiromeninae, 
possibly Chonetoidea itself, became widely distributed along the southeast margin 
of the Caradocian seas, perhaps helped by having become epiplanktonic through 


SHELL STRUCTURE 


Nn 
N 


their ability to fix to marine algae (Bergstrom 1968). Within this stock posterior 
‘hold fasts’ retained the ability to secrete shell material, so evolving tissue-filled 
posteriorly directed spines. Like their ancestors the spat would have been attached 
by their pedicle to hard material on the sea-floor, or perhaps to seaweeds. 
However, at an early age the pedicle atrophied and the development of the spines 
would have helped stabilize benthonic specimens residing in areas subject to marine 
currents, particularly those specimens facing into the current which were 
consequently more susceptible to being overturned posteriorly when the shell 
opened. In a low velocity unidirectional flow from front to back a ‘dead water’ 
zone behind the raised dorsal valve might have prevented the burial or erosion of 
the spines spread out more or less at the sediment to water interface. These 
adaptations contributed to the evolution of the Chonetacea in the Lower 
Palaeozoic fine-grained sedimentary environments in which they are commonly 
found. During Upper Palaeozoic times chonetaceans spread into regions of coarse 
shelly detritus as well as living in silt and mud environments. 


<< Marine flow 


SS 


° 


° ° ° 
Cie Cm cy 


ex) ° 
OGl. = 

° Po 5 9 0° 
° 


Fic. 8. Hypothetical chonetacean adult community on a soft-bottomed sea floor. The 
two shells at the top right are dead; one overturned (seen in transverse section), the 
other part buried. The other three specimens are living (with marginal setae). The 
two front specimens are cut in longitudinal section; on the left parallel to and on the 
right along the median line. In these specimens musculature, body wall and lophophore 
are represented and the arrows indicate the possible flow of water within the brachial 
cavity. 


CHONETACEAN BRACHIOPODS 23 


The spread of chonetaceans to Britain and Europe would have been achieved by 
Williams’ northeasterly oceanic flow, together with the more general break-down in 
provinciality which started at the close of the Ordovician and became marked during 
the mid- and upper Silurian. 

Representatives of the Chonetacea were the first brachiopods to have developed 
long tubular spines. Ontogenetic studies of Carboniferous species indicate that 
these spines normally grew posteriorly at the time of their origin. Thus, in relation 
to the commissural plane the lateral spines at any particular growth stage were 
directed posteriorly and were well suited for the support of shells on the substrate. 
If there was a directional water flow in the environment and if the young shell was 
able to choose its orientation on settlement it is likely that the water circulatory 
system outlined above would best have been served by facing into that flow. In 
this situation posteriorly directed spines are well adapted to the stabilization of the 
shell (Text-fig. 8). 

This demonstration of a gradual change in the shell microstructure from certain 
Plectambonitacea species to Chonetacea species supports the contention of 
Williams & Wright (1967) and others that we have here an evolutionary sequence; 
one which ranges across a subordinal division of the classification in the Treatise. 
Furthermore, the greater complexity discovered within the skeletal fabrics of these 
strophomenids allows wider speculation upon phylogenetic relationships and the 
modification of the relationships suggested by Williams in 1968 and 1970. The 
phylogenies of the superfamilies presented here (Text-fig. 7) are poorly understood 
at the points of origin of the Productacea and Thecideacea. Williams (1970) 
derived the Triplesiacea from the Davidsoniacea which arose from the Billingsellidae. 
In his view the nisusiid Billingsellacea gave rise to the Orthacea, Clitambonitacea, 
Gonambonitacea, Strophomenacea and Plectambonitacea. 


VII. ACKNOWLEDGEMENTS 


This study would not have been possible without the generous donation or loan 
of specimens from various sources, in particular I want to thank my colleague Dr. 
L. R. M. Cocks, Dr. G. A. Cooper of the National Museum of Natural History, 
Washington D.C., Dr. O. A. Dixon of the University of Ottawa, Dr. V. Havlicek of 
the Geological Institute, Prague, Dr. V. Jaanusson of the Natural History Museum, 
Stockholm, Dr. W. D. I. Rolfe of the Hunterian Museum, Glasgow and Dr. A. 
Roomusoks of Tartu, Estonia SSR. I appreciate the stimulating and helpful 
discussions held with several colleagues especially Dr. Cooper (Washington), 
Professor A. Williams ot Queens University, Belfast and Dr. Cocks who were good 
enough to comment upon the draft script, and Mr P. Minton of the Civil Engineering 
Department, Imperial College, London, and am grateful to the Director of the 
British Museum (Nat. Hist.) who granted leave of absence allowing me to visit the 
National Museum of Natural History, Washington. I have received valuable 
assistance from the staff of the Electron Microscope Unit and Photographic 
Department of this Museum. 


24 SHELL STRUCTURE 


VIII. REFERENCES 


ARMSTRONG, J. 1969. The cross-bladed fabrics of the shells of Tevvakea solida (Etheridge and 
Dun) and Stveptorhynchus pelicanensis Fletcher. Palaeontology, London, 12, (2) : 310-320, 
pls 57-60. 

Atkins, D. 1960. The ciliary feeding mechanism of the Megathyridae (Brachiopoda), and 
the growth stages of the lophophore. J. mar. biol. Ass. U.K., Plymouth, 39 : 459-479. 

Baker, P. G. 1970. The growth and shell microstructure of the thecideacean brachiopod 
Moovrellina granulosa (Moore) from the Middle Jurassic of England. Palaeontology, 
London, 13 (1) : 76-99, pls 18-21. 

BERGSTROM, J. 1968. Some Ordovician and Silurian brachiopod assemblages. Lethaia, Oslo, 
10 (3) : 230-237, figs I-9. 

Bovucot, A. J. & Harper, C. W. 1968. Silurian and Lower Middle Devonian Chonetacea. 
J. Paleont., Tulsa, 42 (1) : 143-176, pls 27-30. 

Brunton, C. H.C. 1968. Silicified brachiopods from the Viséan of County Fermanagh (II). 
Bull. By. Mus. nat. Hist. (Geol.), London, 16 (1) : 1-70, pls 1-9. 

1969. Electron microscopic studies of growth margins of articulate brachiopods. Z. 
Zellforsch., Berlin, 100 : 189-200, 13 figs. 
1971. An endopunctate rhynchonellid brachiopod from the Viséan of Belgium and 

Britain. Palaeontology, London, 14 (1) : 95-106, pls 11, 12. 

Brunton, C. H. C. & MacKinnon, D. I. (In press) The systematic position of the Jurassic 
brachiopod Cadomella. Palaeontology, London, 15. 

Cuao, Y. T. 1928. Productidae of China. II. Chonetinae, Productinae and Richthof- 
eniinae. Palacont. sinica, Peking, B.5 (3) : 1-103, pls 1-6. 

Cocks, L.R.M. 1970. Silurian brachiopods of the Superfamily Plectambonitacea. Bull. Br. 
Mus. nat. Hist. (Geol.), London, 19 (4) : 141-203, pls I-17. 

Cooper, G. A. & Grant, R.E. 1969. New Permian brachiopods from West Texas. Smithson. 
Cont. Paleobiol., Washington, 1 : 1-20, pls 1-5. 

Cowen, R. & Rupwick, M. J. S. 1966. A spiral brachidium in the Jurassic Chonetoid 
brachiopods Cadomella. Geol. Mag., London, 103 (5) : 403-406. 

GRaAnT, R. E. (in press). 

Haviicex, V. 1967. Brachiopoda of the suborder Strophomenidina in Czechoslovakia. 
Rozpr. Ustred. Ustav. Geol., Praha, 33 : 1-235, pls 1-52. 

Haviicek, V. & VANEK, J. 1966. The biostratigraphy of the Ordovician of Bohemia. 
Sbornik geol. Ved., paleont., Praha, 8 : 7-69, pls 1-16. 

Koztowski, R. 1929. Les Brachiopodes gothlandiens de la Podolie polonaise. Palaeont. 
Polon., Warsaw, 1 : 1-254, pls 1-12. 

Lister, T. R., Cocks, L. R. M. & Rusuton, A. W. A. 1970 (for 1969). The basement beds 
of the Bobbing borehole, Kent. Geol. Mag., London, 106 (6) : 601-603. 

McCammon, H. M. 1969. The food of articulate brachiopods. J. Paleont., Tulsa, 43 (4) : 
976-985. 

Murr-Woop, H.M. 1962. On the Morphology and Classification of the Brachiopod Suborder 
Chonetoidea. Bry. Mus. nat. Hist., London, VIII + 132 pp., 16 pls. 

Opix, A. A. 1933. Uber Plectamboniten. Acta comment. Univ. tartu geol., Dorpat, 24: 
I-79, pls. 1-12. 

PAECKELMANN, W. 1930. Die Fauna des deutschen Unterkarbons, Die Brachiopoden, 1 Teil. 
Preuss. geol. Landesanst Abh., 122 : 144-326, pls 9-24. 

REED, F. R.C. 1944. Notes on some new Ordovician brachiopods from Girvan. Ann. Mag. 
nat. Hist., London, 11 : 215-222, pl. 3. 

Rupwick, M. J.S. 1961. The feeding mechanism of the Permian brachiopod Provichthofenia 
Palaeontology, London, 3 (4) : 450-471, pls 72-74. 

—— 1968. The feeding mechanisms and affinities of the Triassic brachiopods Thecospiva 

Zugmayer, and Bactrynium Emmrich. Palaeontology, London, 11 (3) : 329-360, pls 65-68. 

1970. Living and fossil bvachiopods. 199 pp. Hutchinson Univ. Lib., London. 


CHONETACEAN BRACHIOPODS 25 


SARYCHEVA, T. G. & SoxotsKayaA, A. N. 1959. ‘The Classification of the Pseudopunctate 
Brachiopods’. Doklady Akad. Nauk SSR, Leningrad, 125, 1 : 181-184 (in Russian). 
TERMIER, H., TERMIER, G. & Payaup, D. 1967. Découverte d’une Thécidée dans le Permien 

du Texas. Comp. Rend. Acad. Sci, Paris, 263 : 332-335. 
Wiitiams, A. 1956. The calcareous shell of the Brachiopoda and its importance in their 
classification. Biol. Rev., Cambridge. 31 : 243-287. 
1968. Evolution of the shell structure of articulate brachiopods. Spec. Papers 
Palaeontology, Londen, 2 : 1-55, pls. 1-24. 
W 1969. Ordovician faunal provinces with reference to brachiopod distribution, in The 
Pre-Cambrian and Lower Palaeozoic Rocks of Wales. (Ed. Wood A.) : 117-154, Univ. 
aloes Press, Cardiff. 
t9Z- Origin of laminar-shelled articulate brachiopods. Lethaia, Oslo, 3 : 329-340, 
figs I-10. 
es A. et al. 1965. Tveatise on Invertebvate Paleontology. Ed. Moore, R. C., Pt. H. 
Brachiopoda. 927 pp., 746 figs, Kansas. 
WitiiaMs, A. & Wricut, A. D. 1967 in Harland, W. B. e¢ al (Eds.). The Fossil Record 
Brachiopoda : 397-421, Geol. Soc., London. 
Wricut, A.D. 1970. A note on the shell structure of the triplesiacean brachiopods. Lethaia, 
Oslo, 3 : 423-426, 2 figs. 


Locality details of figured specimens. 


PLECTAMBONITACEA 

Leptestia musculosa Bekker, Uhaku (Cic) [Upper Llandeilo] Lower Ordovician 

of Uhaku, Estonia . ; : 0 3 : : 0 : c Plate 5 
Leptelloides leptelloides (Bekker), Kukruse oe) [Low Caradoc] Upper 

Ordovician of Kuttejou, Estonia . é 3 c : Plate 5 
Sowerbyella (Viruella) liliifera Opik, enteecee (Cu) {Low Caradoc] Upper 

Ordovician of Estonia 6 5 : : : Plate 2 
Eoplectodonta transversalis (ivanieabers)s Lone? ees, Marl, Llandovery, 

Lower Silurian of Nyhamn, Gotland, Sweden 5 Plates 1-3 
Aegivomena aquila (Barrande), Zahorany Formation [Mid- Cede] nee: 

Ordovician of central Bohemia . Plates, 3, 4 
Aegivia grvayt (Davidson), Upper Wenlock: Sladen, vei Dynes, eneester 

shire, England . : Plate 4 
Sevicoidea vestricta (Hadding), Reh Acdyvell Gaon (Upper Caradoc) Upper 

Ordovician of Craighead, Girvan, Scotland . Plates 4, 5 

CHONETACEA 


Strvophochonetes primigenius (Twenhofel), Ellis Bay Formation [Ashgill] 
Upper Ordovician of Mile 5, Jupiter River and Mile 2, 47 Mile Road, 
Anticosti Island, Canada. (Mile 2 locality is 15-20’ above the base of the 
Ellis Bay Formation: Mile 5 is close to the top junction of the Ellis Bay 
Formation with the Becscie.) —im lit. TE Bolton, Geological Survey of 


Canada, Ottawa) : : 9 : : ‘ 5 : 5 ° Plates 5, 6 
Dawsonelloides canadensis (Billings), Grande Greve Limestone, Siegenian, 
Lower Devonian of Gaspé, Quebec, Canada . : 5 5 : : Plate 7 


Retichonetes vicinus (Castelnau), Arkona Shale, Hamilton Group. Mid 

Devonian, 4 ml. upstream from Hungry Hollow Br., 2 ml. E of Arkona, 

Ontario, Canada : : 5 : Plates 1, 7 
Rugosochonetes silleesi Beaten, high Glener Limestone Low D zone 

Viséan, Lower Carboniferous, of Sillees R, nr. Bunnahone Lough, 2 ml. NW 

of Derrygonnelly, Co. Fermanagh, N. Ireland : - : : : Plates 7, 8 


26 SHELE STRUCTURE 


STROPHALOSIACEA 


Devonalosia wrightorum Muir-Wood & Cooper, Lower Ferron Point shale, 
Hamilton Group, Mid-Devonian of abandoned Ps Portland Cement 
Co. pit, Alpena, Michigan, USA é 5 : ‘ 


PRODUCTACEA 


Helaspis luma Imbrie, Genshaw Formation, Hamilton Group, Mid-Devonian 
of Long Lake, 74 ml. NNE of Alpena, Michigan, USA . : : c 

Eomarginifera lobata (J. de C. Sowerby), Great Limestone, E2 Lower 
Namurian of Greenleighton, Northumberland, England . : 

‘Dictyoclostus’ sp, Carwood, Lower Mississippian of 2 ml. SW of Borden, 
Indiana, USA 

Horridonia horrida (J. Sorcyl lower Teen Pemmere e rsbuiby, 
Gera, Germany . : 


Howarp Brunton, Ph.D. 
Department of Palaeontology 

BritisH Museum (NATURAL History) 
Lonpon, SW7 5BD 


Plate 8 


Plate 9 
Plate 9 
Plate 9 


Plate 9 


S 


PLATE 1 
Pseudopunctae 


Fic. 1. Fracture through a pseudopunctum, with taleola, close to the anterior margin of 
the dorsal valve of Rugosochonetes silleesi Brunton, from Viséan shales of Co. Fermanagh, 
N. Ireland. Eroded internal surface is to the bottom, viewed posteriorly. SEM (Scanning 
electron microscope), 1150. 


Fic. 2. Deeply exfoliated dorsal valve exterior of Retichonetes vicinus (Castelnau) 
from the middle Devonian Arkona Shale of Ontario, Canada, showing ribbing and a taleola 
within a pseudopunctum. The exterior of the shell is uppermost and the anterior is to the top. 
SEM, x 440. 


Fic. 3. Deeply exfoliated dorsal valve interior of Aegiromena aquila (Barrande) from 
the Caradoc of Czechoslovakia, showing a completely ‘fibrous’ pseudopunctum. The valve 
interior is to the top. SEM, x1tIoo. 


Fic. 4. The internal mosaic surrounding a pseudopunctum of Eoplectodonta transversalis 
(Wahlenberg), from the Llandovery of Gotland, Sweden. The anterior margin of the valve is 
to the right. SEM, x550. 


Bull. By. Mus. nat. Hist. (Geol.) 21, 1 PLATE 1 


PEATE 2 
Sowerbyellinae, standard shell fabric 


Fics 1-3. Sowerbyella (Viruella) liliifera Opik from Low Caradoc of Estonia. Valve 
interiors to the top. 1 -— Cut and lightly etched transverse section of the ventral valve showing 
typical secondary fibres. SEM, x1o0oo. 2-— Fractured dorsal valve interior viewed posteriorly , 
showing the three dimensional aspect of typical secondary fibres. SEM, tooo. 3 — Trans- 
verse fracture, close to dorsal valve margin, showing the transition from the sediment and 
primary shell, near the bottom, to secondary fibres at the top. SEM, x 1000. 


Fics 4-6. Eoplectodonta transversalis (Wahlenberg) from the Llandovery of Gotland, 
Sweden. Valve interiors to the top. 4 — Latex impression of a ventral valve interior, i.e. an 
internal mould, showing the mantle canal impressions extending from deeply impressed 
lanceolate diductor muscle scars. 3. 5 — Detail of the umbonal region of fig. 4 showing 
the small medianly placed adductor muscle scars. x6. 6 — Transverse fracture through the 
external region of the valve showing, from bottom up, a thin layer of micrite, small lath-like 
primary lamellae and the start of standard secondary fibres. SEM, 1200. 


Bull. By. Mus. nat. Hist. (Geol.) 21, 1 PLATE 2 


PLATE 3 
Eoplectodonta and Aegiromena 


Fics 1-4. Eoplectodonta transversalis (Wahlenberg) from the Llandovery of Gotland, 
Sweden. Interior surfaces to the top. 1 — General view of the dorsal valve interior showing 
the prong-like elongations, despite broken tips, of the socket ridges. 3. 2 — Exfoliated 
dorsal valve interior, about 1.5 mm. behind the anterior margin, showing pseudopunctae and 
several small endopunctum-like flexures of the secondary fibres (arrowed). SEM, 250. 3 — 
Detail of endopunctum-like flexures, seen in section, from centre of fig. 2. SEM, x 3000. 
4 — Detail of the internal surface, slightly exfoliated, showing the same flexures. SEM, 1200. 


Fic. 5. Aegiromena aquila (Barrande) from the Caradoc of Czechoslovakia. Deeply 
exfoliated dorsal valve interior (to the top right) near the antero-lateral margin and close to 
the external surface showing one of the rarely occurring almost typical secondary fibres. The 
antero-lateral margin is to the bottom. SEM, 1200. 


ATE 3 


IPL, 


Mus. nat. Hist. (Geol.) 21, 1 


Bull. Br. 


4 P 


> 


om 


owt 
yo 


PLATE 4 
Aegiromeninae 


Fics 1, 2. Aegiromena aquila (Barrande) from the Caradoc of Czechoslovakia. _1— 
Exfoliated dorsal valve, about half way through the shell and towards the antero-median 
margin, showing a pseudopunctum with taleola. Anterior is to the top. SEM, x1100. 2 — 
Exfohated ventral valve exterior showing ribbing, distribution of pseudopunctae, mainly 
within the rib interspaces, and parallel fibrous nature of the shell. Anterior is to the top. 
SEM, x120. 


Fic. 3. Deeply exfoliated ventral valve interior, close to the external surface, of Aegiria 
grayi (Davidson) from the mid-Silurian of Dudley, England, showing almost standard parallel 
fibres of the secondary layer. Interior is to the top left. SEM, x 1800. 


Fic. 4. Exfoliated ventral valve exterior, near the antero-lateral margin, of Sericoidea 
restricta (Hadding) from the Caradoc of Girvan, Scotland, showing intermediate, atypical 
‘fibres’. Anterior is to the top. SEM, x 1000. 


4 


IPL NATE 


nat. Hist. (Geol.) 21, 1 


Mus. 


Bull. Br. 


PLATE 5 


Fics 1, 2. Sericoidea restricta (Hadding) from the Caradoc of Girvan, Scotland. Ex- 
teriors to the top. 1 —  Exfoliated ventral valve exterior showing subparallel ‘fibres’. Antero- 
lateral margin to the left. SEM, «1250. 2 —Slghtly exfoliated ventral valve exterior close 
to its antero-median margin showing a single layer of small primary shell lamellae with sub- 
parallel ‘fibres’ below, including one near-normal transverse section (arrowed). Anterior is to 
the bottom. SEM, x 1000. 


Fic. 3. Broken section near the anterior margin of the dorsal valve of Leptelloidea leptel- 
loides (Bekker), from low Caradoc of Estonia, showing the typical secondary layer fibres of 
the non-aegiromeninid Plectambonitacea. Exterior to the top. SEM, 1250. 


Fic. 4. Deeply exfoliated ventral valve exterior, near the posterior margin, of Leptestia 
musculosa Bekker from the Upper Llandeilo of Estonia, showing typical secondary shell of 
the early Plectambonitacea. Interior uppermost. SEM, x 1ooo. 


Fics 5-8. Strophochonetes primigenius (Twenhofel) from the Ellis Bay Formation, 
Ashgill, of Anticosti Island, Canada. 5 — Interior of a young dorsal valve. 4. 6— Posterior 
view of a dorsal valve showing the quadrifid myophore of the cardinal process and low flanking 
chilidial plates (arrowed on one side). 9g. 7 — Ventral valve exterior and part of a dorsal 
valve interior. x3. 8 — Detail of the dorsal valve cardinalia, note the strongly bilobed 
cardinal process. 4. 


itp 2 


2 


nat. Hist. (Geol.) 


Bull. Br. Mus. 


PEATE 6 


Strophochonetes primigenius (Twenhofel) 
from the Ellis Bay Formation of Anticosti Island, Canada. 


Fies 1, 2. Deeply exfoliated ventral valve exterior, close to the antero-lateral margin (to 
the top) showing pseudopunctae and the disposition of secondary transitional ‘fibres’. SEMs, 
«550 and x 1000. 


Fic. 3. Well preserved ventral valve exterior showing the bases of spines and the accentuated 


median rib. x3. 


Fic. 4. Part of one of the fossiliferous slabs of limestone showing many ventral valve ex- 
teriors and one dorsal valve interior (figured PI. 5, fig. 5). The accentuated median rib, typical 
of Strophochonetes and spine bases show on most specimens. » 2. 


Bull. By. Mus. nat. Hist. (Geol.) 21, 1 IPILIN W138, © 


PLATE 7 
Devonian and Lower Carboniferous Chonetacea 


Fics 1, 2. Dawsonelloides canadensis (Billings) from the Lower Devonian of Gaspé, 
Ouebec, Canada. Valve exteriors uppermost. 1 — Deeply exfoliated exterior at a pseudo- 
punctum with taleola. SEM, x960. 2 — Small fibre-like units close to the external surface 
showing some lateral fusion. SEM, x 4000. 


Fic. 3. Retichonetes vicinus (Castelnau) from the Mid-Devonian of Ontario, Canada. 
Slightly exfoliated ventral valve interior, at a pseudopunctum with taleola, showing the fusion 
of lath-like elements to give impersistent sheets. Antero-lateral margin to the bottom left. 
SEM, x 1100. 


Fic. 4. Rugosochonetes silleesi Brunton from the Viséan of Co. Fermanagh, N. Ireland. 
Slightly exfoliated internal surface of a dorsal valve postero-medianly. Anterior is to the 
right. The individual shell lamellae are thin and do not retain a parallel orientation from 
layer to layer. SEM, x 2100. 


Bull. By. Mus. nat. Hist. (Geol.) 21, 1 PLATE 7 


PAGES 


Fics 1-3. Rugosochonetes silleesi Brunton from the Viséan of Co. Fermanagh, N. 
Ireland. Dorsal valve exterior uppermost. 1 — Somewhat eroded external surface of the 
valve showing thin laminae forming wide sheets. SEM, 1100. 2 — Detail from the centre 
of fig. 1 showing surfaces within the laminae like those onto which shell growth may have 
occurred in the living animal. SEM, 5500. 3 — Fracture surface a little below the valve 
exterior (to the top) and close to the valve margin (to the bottom right) showing sheets of thin 
blade-like laminae. The sheet surface is broken by persistent and impersistent grooves which 
in life accommodated organic material separating individual blades. The ridges, at 20° to 30° 
from the grooves, mark the interblade boundaries of the adjacent removed sheet. SEM, x 2600. 


Fic. 4. The strophalosiacean Devonalosia wrightorum Muir-Wood & Cooper, from the 
Mid Devonian of Michigan, U.S.A. Fracture surface near the anterior margin of the dorsal 
valve. The exterior is just off the top of the micrograph. Well-differentiated units resembling 
crested laminae.SEM, x 2200. 


PLATE 8 


Bull. By Mus. nat. Hist. (Geol.) 21, 1 


PLATE 9 
Productacea 


Fic. 1. Helaspis luma Imbrie, from the Mid-Devonian of Michigan, U.S.A. showing 
external surfaces of crested laminae with subparallel orientation. SEM, x 2800. 


Fic. 2. Eomarginifera lobata (J. deC Sowerby), from the Lower Namurianof Northumber- 
land, England, showing cross-bladed structure near the centre of the base of the trail. Exterior 
to the top, anterior to the left. SEM, 2000. 


Fic. 3. ‘Dictyoclostus’ sp. from the Low Mississippian of Indiana, U.S.A. showing cross- 
bladed fabric on an exfoliated interior from the ventral valve trail. SEM, x 4000. 


Fic. 4. Horridonia horrida (J. Sowerby), from the Permian of Germany, showing typical 
cross-bladed fabric close to the external surface of the ventral valve near the postero-lateral 
margin. Exterior to the top right. SEM, x 4000. 


Bull. By. Mus. nat. Hist. (Geol.) 21, 1 PLATE 9 


“A LIST OF SUPPLEMENTS == 

TO THE GEOLOGICAL SERIES 

OF THE BULLETIN OF oe. 

THE BRITISH MUSEUM (NATURAL HISTORY). : 


Pp. 213: 30 Plates; 2 Text-figures. 1965. £6, 
. Et-Naccar, Z. R. Stratigraphy and Planktonic Rotaniinieee 0! 
Cretaceous—Lower Tertiary Succession in the Esna-Idfu Region, 
Egypt, U.A.R. Pp. 291; 23 Plates; 18 Text-figures. 1966. {10. 
. Davey, R. J., Downie, C., SARGEANT, W. A. S. & WiLztams, G. L. 
Mesozoic and Cainozoic ‘Dinoflagellate Cysts. Pp. 248; 28 Plat 
figures. 1966. {7. : 
. APPENDIX. Davey, R. J., Downie, C: SARGEANT, W. As S. & W 
_ Appendix to Studies on Mesozoic and Cainozoic Dinoflagellate C 
1969. 8op. ; 
;-Evviortr, G. F. Permian to Palaeocene Calcareous Algae @asydad uC 
Middle East. Pp. 111; 24 Plates; 17 Text-figures. 1968. £5.12}. 
. Ruopes, F. H. T., Austin, R. L. & Druce, E. C. British Avo: 
ferous) Conodont Ems; and their value in local and continental 01 
Pp. 315; 31 Plates; 92 Text-figures. 1969. 11. — é ; 
. CuiLps, A. Upper Jurassic Rhynchonellid’ Brachiopods from 
Europe. Pp. 119; 12 Plates; 40 Text-figures. 1969. £4.75. 
. Goopy, P. C. The relationships of certain Upper Cretaceous 
special reference to the Myctophorids. Pp. 255; 102 Text-figures. 
. OwEN, H. G. Middle Albian Stratigraphy in the ‘Paris ‘Ba 
3 Plates; 52 Text-figures. 1971. {6.. 
. Sippigur, Q. A. Early Tertiary Ostracoda of the: family ‘Tr 
from West Pakistan. Pp. 98; 42 Plates; 7 Text-figures. 1971. 


| a oo 
3 oO 
3 shes 
zi ¥ a Q 
a 
oe e a es 


__ TRITYLODONTIDS 
CROMPTON 


z 


5 


SEUM 


- 


ULLETIN OF 
(N 


* 
1 


SH M 


NINE OCCLUSION I 


vA 


‘ 


POSTCANINE OCCLUSION IN CYNODONTS 


AND TRITYLODONTIDS pe 
$0 JAN 1973 


BY 


ALFRED WALTER CROMPTON 


Museum of Comparative Zoology, Harvard University, 
Cambridge, Mass. 


Pp. 27-71; 7 Plates, 14 Text-figures 


BOLLE TIN’ OF 
THE BRITISH MUSEUM (NATURAL HISTORY) 
GEOLOGY Vol. 21 No. 2 
LONDON : 1972 


THE BULLETIN OF THE BRITISH MUSEUM 
(NATURAL HISTORY), instituted im 1949, 1s 
issued in five series, corresponding to the Departments 
of the Museum, and an Historical serves. 


Parts will appear at irregular intervals as they become 
veady. Volumes will contain about three or four 
hundred pages, and will not necessarily be completed 
within one calendar year. 


In 1965 a separate supplementary series of longer 
papers was instituted, numbered serially for each 
Department. 

This paper ts Vol. 21, No. 2 of the Geological series. 
The abbreviated titles of periodicals cited follow those 
of the World List of Scientific Periodicals. 


World List abbreviation 
Bull. Br. Mus. nat. Hist. (Geol.). 


© Trustees of the British Museum (Natural History), 1972 


TRUSTEES OF 
THE BRITISH MUSEUM (NATURAL HISTORY) 


Issued 29th December, 1972 Price £3.40 


POSTCANINE OCCLUSION IN CYNODONTS 
AND TRITYLODONTIDS 


By A. W. CROMPTON 


CONTENTS 

I. INTRODUCTION : : ; : : 30 

II. PosSTCANINE DENTITION OF THE , PROCYNOSUCHIDAE AND 
GALESAURIDAE : c : . : 32 

III. PostcANINE DENTITION OF THE  DIADEMODONTIDAE AND 
TRIRACHODONTIDAE : : : : : 35 
IV. PostcANINE DENTITION OF THE “TRAVERSODONTIDAE é : : 40 
1. Description of three new species of Scalenodon 3 41 
2. Occlusion and jaw movements in Scalenodon Pisa POS 44 
3. Occlusion and jaw movements in Scalenodon hirschson . 49 
4. Postcanine dentition of Scalenodon attridger . b : 53 
5. Postcanine dentition of Scalenodon charigi . : : 54 

6. Occlusion and jaw movements in a species of 
Massetognathus . é : 56 
7. Postcanines of Exaevetodon ed Capp nod onioen sie é 58 
V. DiIsTRIBUTION OF THE TRAVERSODONTIDAE A 60 
VI. Occtustion In Tritylodon AND THE ORIGIN OF THE Stee eaon gaan 61 
VII. SUMMARY AND DISCUSSION 5 - < : : é : 64. 
VIII. AcKNOWLEDGEMENTS Z : : : : 5 : 5 68 
IX. REFERENCES . ‘ ; : : ‘ : : : : 69 
SYNOPSIS 


Within the gomphodont cynodonts and their descendants, the tritylodontids, it is possible to 
trace the initiation and progressive improvement of postcanine occlusion and complex masti- 
catory movements, beginning with primitive cynodonts in which mastication did no¢ involve 
actual contact between matching upper and lower postcanine teeth. Occlusion in advanced 
cynodonts was functionally similar to that of primitive mammals with tribosphenic molars, 
and the mechanisms by which occlusion evolved in the two groups also appear to have been 
similar. In primitive gomphodont cynodonts and primitive mammals the crowns of occluding 
teeth had to be moulded by wear to produce accurately matching shearing surfaces; major 
features of the crown were thereby obliterated. In advanced members of both groups the 
topography of the crowns was modified so that only a little wear was needed to produce matching 
shearing planes. 

A clear correlation appears to have existed between the occlusal relationships of the teeth of 
cynodonts and their replacement patterns. The enamel of cynodonts and tritylodontids was 
thin and apparently worn through rapidly, so that the structure of the crowns was soon 
destroyed; in order to compensate for this, worn gomphodont teeth were lost from the front of 
the row and new ones added behind. 

The tritylodontids were probably derived from traversodont cynodonts. The longitudinally 
orientated shearing planes on the postcanine teeth became more numerous and the relative 
extent of the backward movement of the lower jaw during the final stages of mastication was 
progressively increased. 


Three new species of traversodont cynodonts are named (Scalenodon hirschsoni, S. attridget, 
S. charigi). 


30 POSTCANINE OCCLUSION 


INTRODUCTION 


ACCURATE occlusion between cheek teeth with complex crown patterns is a mammal- 
ian character. It involves complicated relationships between the cusps, ridges and 
basins of occluding teeth and also mandibular movements that are seldom directly 
orthal during the final stages of the masticatory cycle (power stroke, Crompton & 
Hiiemae, 1969a & 6), but are also partially transverse and forward. The relative 
amount of upward, forward and sideways movement during this phase of occlusion 
differs widely in the various mammalian orders. Many of the advanced cynodonts 
and tritylodontids independently developed occlusal patterns which in terms of 
function closely parallel those of later mammals. The purpose of this paper is to 
describe and discuss the development of postcanine occlusion in several groups of 
cynodonts, which are the most mammalian of the therapsid reptiles and the group 
from which mammals almost certainly arose. Although the cynodonts which had 
dental occlusion and which are discussed in this paper were not ancestral to mammals 
this study does throw some light on the mechanism involved in developing dental 
occlusion of the mammalian type. 

Numerous authors have described and discussed the morphology of the teeth of 
therapsid reptiles; but few have described occlusal relationships, and except for one 
or two cases (Watson 1911, Parrington 1946) no attempt has been made to determine 
jaw movements during mastication or dynamic occlusion of the cheek teeth of this 
group. The functional aspects of mammalian occlusion also have been neglected, 
but recent papers on wear facets on the molars of living and extinct mammals 
(Butler, 1961; Mills, 1964, 1966, 1967; Kermack, Lees & Mussett, 1965; Crompton & 
Jenkins, 1967, 1968) and cineradiographic studies of mastication in a primitive 
mammal (Crompton & Hiiemae, 1969, a, b & c) have provided a model with which 
to compare the dynamic occlusal relationships and possible jaw movements in 
cynodonts. 

The infraorder Cynodontia (Fig. 1) arose in the late Permian, reached its greatest 
diversity in the Middle Trias and became extinct in the early part of the Late Trias. 
As will be shown below, the Tritylodontidae which survived until the Middle Jurassic 
can be considered as late survivors of the cynodonts. The Ictidosauria (Diarthro- 
gnathus, Pachygenelus and Trithelodon) were probably also late survivors of the 
Cynodontia and a case can perhaps be made for including them within the cynodonts. 
The cynodonts are usually divided into the following families: the Procynosuchidae 
(I am including genera which have been placed in separate families by some authors, 
e.g. Silphedestidae, Dviniidae, Cynosauridae) ; the Galesauridae; the Cynognathidae; 
the Chiniquodontidae (this family probably includes most of the South American 
carnivorous cynodonts which have not yet been adequately described but which are 
at present being studied by Prof. A. S. Romer) ; the Trirachodontidae; the Diademo- 
dontidae; and the Traversodontidae. The interrelationships and time-spans of 
these families are shown in Figure 1. The last three families are commonly referred 
to as the gomphodont cynodonts and it is only in them that complex occlusion 
between upper and lower postcanine teeth occurred. Postcanine occlusion is present 
in the Ictidosauria, but it is not complex. The Traversodontidae were the most 
varied and abundant of the cynodonts and their remains have been discovered in the 


ee EEE 


31 


CYNODONTS AND TRITYLODONTIDS 


“UMOUY SIV SUIIOF 0} eIpoUT 
-19}UT OU 3nq syuOpouAD ATIe9 0} P9zeToI 9IOM oso} ATJUeIedde ‘aeptyUOposjsoz0g 9y} pure 
seplLey}OouYyon y oy} ‘(YOe]q) sorprurey [PUIUIe 4SOTLIV9 OM OY} Oe UMOYS OSTY “(peyoreU 
Ayyeorz19A) sorprurey yuopouds isofeur oy} Fo sdrysuorejeiiezur pue sueds-ouny “1 ‘DI 


mM >~ 
N 


VIENVSOCGILD! ~ 


AVGILNOGOYLSOZO3 RF. ee ee 


ITT 
3VGIYSHLOANHSN yp” onol 


TUTE 
NIBO HD} — — — — — — 
| HI 


TTT 
LNO 


AVAILNOGOTALIYNI 


MET fe ee Ser Lees rol. i. oer = 
oIssvuner AS Seaeul NVINYSd 


32 POSTCANINE OCCLUSION 


Middle Trias of East Africa, Late Trias of South Africa and in great abundance in the 
Trias of South America (see Crompton, 1955; Crompton & Ellenberger, 1957; 
Bonaparte, 1967a&b; Romer, 1967; and Sill, 1969 for pertinent literature). Numerous 
representatives of the remaining cynodont families have been found in the sedi- 
mentary rocks of the Karoo system of South Africa (Haughton & Brink, 1954 and 
Lehman, 1961 for pertinent literature), although they are also known from South 
America (Bonaparte, 1967a & b), China (Young, 1959 & 1961) and Russia (Tatarinov, 
1968). Dental occlusion (i.e. toorh-to-tooth contact) is absent in the Procyno- 
suchidae and Galesauridae but, as members of these families are ancestral to the 
later gomphodont cynodonts, their postcanine dentitions will be briefly considered. 


II. POSTCANINE DENTITION OF THE PROCYNOSUCHIDAE AND GALESAURIDAE 


The postcanine dentition of the Procynosuchidae is best known in the South 
African species Leavachia duvenhagei. Ina recent review of procynosuchid literature 
Anderson (1968) suggested that Procynosuchus, Galecranium and Galeophrys were 
probably synonymous with Leavachia; the postcanine row of Leavachia duvenhaget 
consisted of 7 to 11 teeth according to the age of the individual. Alternate tooth 
replacement was observed in all specimens studied. 

Mendrez (1967) figured the postcanines of an unidentified species of Leavachia. 
The crowns of postcanines from the middle of the row were circular in cross-section 
while those further back were longitudinally ovate (Fig. 2A). A large external cusp 
was present. On the internal edge of the crowns of both upper and lower teeth there 
was a series of small cusps, the most anterior and posterior of which were visible in 
external view; in this view therefore, the crown appeared to be tricuspid. In lateral 
view it could be seen that upper and lower postcanines alternated with one another; 
the centre of the lower tooth lay medial to the space between two upper teeth. The 
lower postcanines bit medial to the uppers but because there was no contact between 
upper and lower teeth matching shearing surfaces did not develop. The postcanines 
of these early cynodonts were therefore capable of gripping, puncturing and possibly 
crushing food but could not shear food efficiently. 

The postcanine dentition of the aberrant procynosuchid Dvinia prima from the 
Russian Permian was described in detail by Tatarinov (1968), who placed the genus 
in a new family Dviniidae. The postcanine teeth were considerably more complex 
than those of Leavachia. The crowns of the upper postcanines (“‘molars’’) (Fig. 2B). 
were transversely ovate with a central cusp completely surrounded by several small 
cusps on the edge of the crown. Unlike those of Leavachia these cusps were present 
on the external edge of the crown as well as on the internal edge and the external 
cusps were slightly larger than the internals. The lower molars of Duinia prima 
were similar to the uppers except that additional cusps were present in the centre of 
the crown medial to the main cusp. The postcanines of Dvinia prima could have 
been derived from those of Leavachia by the addition of a series of small external 
cusps. In Dvinia upper and lower canines did not occlude, i.e. there was no tooth- 
to-tooth contact, and the lower postcanines bit medial to the uppers. In these 
respects the teeth of Dvinia were superficially similar to those of Leavachia. Because 


CYNODONTS AND TRITYLODONTIDS 


Fic. 2. Galesaurids and procynosuchids. Postcanine teeth. (In these and all other 
text-figures lower teeth are stippled, upper teeth are plain). A. Leavachia. Crown view 
of upper from middle and back of row. After Mendrez, 1967. B. Dvinia prima. 
Crown views of upper and lower. After Tatarinov, 1968. C. Thrinaxodon. Crown 
views of upper and lower. D. Thrinaxodon. Crown views of last four uppers and last 
four lowers. E. Thrinaxodon. Internal views of last four uppers and last four lowers. 
F. Glochinodontoides gracilis. External view of first three uppers. G. Glochinodontoides 
gracilis. Crown view of first three uppers. H. Cynidiognathus. External view of 
posterior lower postcanines. After Fourie, 1964. 


33 


34 POSTCANINE OCCLUSION 


the teeth were transversely ovate they appear to be similar to those of gomphodont 
cynodonts, but in the latter group crown-to-crown occlusion was present. 

Several small Permian cynodont skulls have been described (e.g. Protocynodon, 
Nanictosuchus, Nanictosaurus, Silphedestes ; see Haughton & Brink, 1954 for pertinent 
literature). These appear to have had postcanine teeth similar to those of the 
galesaurid Thrinaxodon liorhinus but until they have been adequately prepared and 
studied their taxonomic position will remain in doubt. It is possible that the fore- 
runners of the Galesauridae will be found among these little-known cynodonts. 

The best-known member of the Galesauridae is Thrinaxodon liorhinus. Several 
undistorted skulls of this species have been prepared with acetic acid and the crown 
patterns and relationships of upper and lower postcanines studied in detail. The 
postcanine teeth did not occlude, replacement was alternate, their crowns were 
longitudinally ovate and both upper and lower crowns (especially the lowers) had a 
well developed internal cingulum which supported several cusps. In Fig. 2C, D& E 
and Plate 1 the postcanines are shown in crown and internal view. It will be seen 
that the upper and lower teeth tended to alternate with one another in position and 
that when the jaws were closed a considerable space separated the outer surface of the 
lower teeth and the inner surtace of the upper teeth. All the specimens studied 
showed this. Asin procynosuchids, the postcanines ot Thrinaxodon did not develop 
matching wear facets on the internal surface of the uppers or external surface of the 
lowers, thus indicating that shearing did not take place; i.e., upper and lower teeth 
did not occlude with one another. Lateral movement of the lower jaws sufficient to 
enable upper and lower teeth to come into contact appears to have been prevented in 
both Galesauridae and Procynosuchidae by the strong transverse processes of the 
pterygoids and the large pits in the palate which accommodated the lower canines. 
Tribolodon from the younger Cynognathus zone had postcanine teeth similar to those 
of Thrinaxodon but the internal cingulum of the lower postcanines was reduced and, 
in the material available for study, I never observed more than two subsidiary cusps 
on the internal surface of either upper or lower postcanines. 

The postcanine teeth of the remaining galesaurid genera, i.e. Galesaurus, Glochi- 
nodon, Glochinodontoides, Platycraniel’us and Cynosuchoides, were distinct from those 
of Thrinaxodon. Upper and lower teeth (Fig. 2F, G; Plate 2) were apparently 
identical and were characterized by a strongly recurved main cusp with a sharp — 
blade-like cusp behind and by a total absence of subsidiary cusps on the anterior or 
internal surfaces. The tip of the main cusp was worn but, as in Thyinaxodon, there 
were no matching shearing surfaces on upper and lower teeth. In a few specimens 
available for study teeth were being replaced, but there appears to have been a 
“break-down” of the alternate tooth-replacement pattern that characterized 
Thrinaxodon and the procynosuchids. The way in which these peculiar teeth 
functioned is not understood. 

Galesauridae with teeth of this type may have been ancestral to the Cynognathidae 
or Chiniquodontidae. In Cynognathus and Cynidiognathus (Fourie, 1964) the post- 
canines usually lacked internal cingula; the main cusp was slightly recurved (Fig. 
2H); and, depending upon the position of a postcanine in the tooth row, one, two or 
three anterior and posterior accessory cusps may have been present. In Cyno- 


CYNODONTS AND TRITYLODONTIDS 35 


gnathus there was no obvious alternate replacement of the postcanines but the 
presence of matching wear facets on the external surface of the lowers and internal 
surface of the uppers shows that the teeth were used for shearing. 


Ill. POSTCANINE DENTITION OF THE DIADEMODONTIDAE AND TRIRACHODONTIDAE 


The earliest known cynodont to develop postcanines with a complex occlusal 
pattern was the gomphodont cynodont Diademodon from the early Trias of South 
Africa. The dentition has been described by Seeley (1895), Watson (1911), Broili & 
Schréder (1935) Brink (1955, 1957), Crompton (1955, 1963), Fourie (1963, 1964), Hopson 
(1971) and Ziegler (1969). The postcanine row was differentiated into two to six 
conical teeth in front; three to nine transversely widened gomphodont teeth in the 
middle; and two to five posterior teeth which range in crown structure from semi- 
gomphodont to fully sectorial (Fig. 3B). The number of teeth present depended 
upon the age of the individual. The upper gomphodont teeth were transversely 
ovate in crown view and wider than the corresponding lower teeth (Fig. 3A—C and 
Plate 2B) so that, when the teeth occluded, the inner and outer margins of the upper 
teeth overlapped the corresponding margins of the lowers (Fig. 14C). The alternate 
tooth replacement characteristic of Thrinaxodon did not occur in Diademodon; the 
details of replacement in the latter genus are not yet fully understood, but it was 
complex, not alternate, and apparently confined to the anterior and posterior regions 
of the postcanine row. At the front of the row sharp conical teeth replaced worn 
gomphodont teeth; at the back gomphodont teeth replaced either semi-gomphodont 
or sectorial teeth. Consequently the occlusal relationships between upper and lower 
gomphodont teeth were never disturbed by replacement in the middle of the row as 
would have been the case if replacement had been of the alternate pattern found in 
the earlier Galesauridae. 

Ziegler (1969) concluded that there was probably no replacement at the back of 
the postcanine row of Diademodon, the pattern being essentially mammalian in that 
only the incisors, canines and anterior postcanines were replaced. His paper was 
based entirely upon published accounts of the dentition. Ziegler correctly pointed 
out inconsistencies both in my own and in other authors’ attempts to interpret the 
tooth replacement pattern that was present in Diademodon, but his conclusions too 
are open to criticism and do not appear to be substantiated by the known material. 

Dr. J. Hopson of the University of Chicago is at present preparing a manuscript on 
tooth replacement in Diademodon and Dr. J. Osborn of the Dept. of Oral Anatomy, 
Guys Hospital, London, is completing a manuscript on the order of tooth eruption 
and replacement in Diademodon and some early cynodonts. Because of this I do 
not wish to enter here into a full discussion of tooth replacement in Diademodon but 
would like to point out some problems raised by Dr. Ziegler’s interpretation. 

In the smallest known specimen of Diademodon (Kitching, private communication) 
the postcanine row contains two or three gomphodont teeth and 1s terminated by 
two or three teeth which appear to have been either semi-gomphodont or sectorial in 
structure. In slightly larger specimens (Brink, 1963b) the postcanine row contains 
five gomphodont teeth with three semi-gomphodont or sectorial teeth behind. In 


36 POSTCANINE OCCLUSION 


still larger specimens (Crompton 1955, 1963b) up to seven gomphodont teeth are 
present with four or five semi-gomphodont or sectorial teeth behind. The Diade- 
modon skulls of different sizes might be considered as different species but this is an 
extremely unlikely interpretation as many were found at one locality (Brink, 1963b) ; 
it is more reasonable to suppose that they represent growth stages of a single species 
(Kitching, 1968). Ziegler appears to have overlooked the size range of the available 
material of Diademodon and the fact that the postcanine row always ends in a series 
of teeth which become progressively more sectorial. It would be impossible to 
obtain the growth stages listed above without replacement at the back of the row. 
In the large series of jaws studied by Fourie (1964) there is clear evidence of the loss 
of some of the anterior conical postcanine teeth, and a specimen of Diademodon in 
East Berlin (Crompton, 1963b) clearly documents the replacement of the most 
anterior gomphodont tooth by aconical tooth. In 1955 I interpreted a longitudinally 
ovate opening below an unerupted posterior postcanine tooth of Diademodon as an 
alveolus, but it seems that Ziegler does not accept this as evidence of replacement of 
a sectorial tooth by gomphodont tooth at the back of the postcanine row. 

Diademodon is closely related to other gomphodont cynodonts such as Tvivachodon, 
Cricodon, Scalenodon and a new and as yet undescribed and unnamed reptile from the 
Ntawere Formation of the Luangwa Valley (Zambia). In a Tvivachodon skull 
prepared by Dr. F. R. Parrington and figured by myself (1963a) there is clear evi- 
dence of the replacement of the sectorial teeth at the end of the postcanine row by 
gomphodont teeth. Ina late survivor of the Trirachodontidae, Cricodon (Crompton, 
1955), a longitudinally ovate foramen containing the root of a sectorial tooth lies 
below an unerupted gomphodont tooth; this foramen is similar in shape and position 
to that found in Diademodon but was clearly an alveolus and not a gubernacular 
canal. In some species of Scalenodon the postcanine row is terminated by small 
gomphodont teeth; unerupted larger gomphodont teeth lay above the small teeth and 
would presumably have replaced them later. This evidence, derived from growth 
stages of Diademodon and from related forms that have been figured or studied in 
South Africa, suggests that the posterior postcanine teeth were replaced during 
growth. Dziademodon may eventually have reached a mature stage when replace- 
ment ceased in the postcanine series and this may explain why in several of the larger 
individuals there is no clear evidence of replacement at the back of the row. Ziegler 
is perhaps unaware that most of the available Diademodon material is poorly pre- 
served and has undergone little or no development; careful preparation of the 
existing material will probably show teeth that were in the process of being replaced 
at the time of death. 

The important points concerning Diademodon are that gomphodont teeth were 
lost in front (or were replaced by conical teeth) ; that they were added behind (by the 
replacement of existing semi-gomphodont or sectorial teeth); and that there is no 
evidence of replacement of gomphodont teeth by gomphodont teeth. Consequently, 
a series of gomphodont teeth always shows a progressive increase in wear towards 
the front; this is hecause of the occlusal relationships of the postcanine teeth. The 
replacement patterns of teeth in gomphodont cynodonts ensured that in Diademodon 
a fresh supply of cusped gomphodont teeth were added during growth and that in 


CYNODONTS AND TRITYLODONTIDS 37 


the later forms a fresh supply of teeth with deep shearing planes were added. In 
gomphodonts the enamel covering the crowns of the teeth appears to have been thin 
and perhaps soft, so that the structure of the crown was soon worn away and the 
teeth were perhaps replaced more rapidly than in mammals. 

The exact order of tooth replacement occurring in the ontogeny of Diademodon is 
not fully understood; it is hoped that further work on material already available will 
clarify this process and meet the objections raised by Dr. Ziegler. 

Crown views of unworn upper and lower gomphodont teeth of Diademodon are 
given in Fig. 3A and Plate 2. The upper crowns were transversely ovate whereas 
the lower crowns tended to be more circular. The upper crown was dominated by an 
external main cusp from which a well-defined ridge ran directly forwards, bearing 
two or three subsidiary cups which became smaller towards the front ; another ridge, 
ill-defined and slightly crenulate, ran backwards from the tip of the external main 


EXTERNAL 


ae 


lcm 


Fic. 3. Diademodontids and trirachodontids. Postcanine teeth. A. Diademodon. 
Crown view of typical upper and lower gomphodont teeth. B. Diademodon. Crown 
views of last five uppers and last four lowers to show shearing surfaces produced by wear. 
C. Asin B, but superimposed as when occluded. D. As in C, occluded, but in internal 
view. E. Cricodon. Crown views of typical upper and lower. For key to abbreviations 
see p. 69. 


38 POSTCANINE OCCLUSION 


cusp. The internal edge of the crown was dominated by two cusps, the anterior and 
posterior internal cusps, which, although smaller than the external cusp, were almost 
as high. The anterior edge of the crown bore a series of four or five small cusps which 
tended to become bigger towards the mid-line. The posterior edge supported one or 
two well-defined cusps of unequal size and a series ot small cuspules or crenulations. 
A series of crenulated ridges radiated from the centre of the crown towards both the 
anterior and the internal cusps, with shallow valleys or basins lying between. A 
series of three or four smaller ridges radiated from the base of the external main cusp 
towards the centre of the crown to terminate in an ill-defined high area which 
supported a series of small cusps and which, together with the ridges radiating from 
the external and internal cusps, formed an ill-defined transverse ridge. A shallow 
occlusal basin was formed between the transverse ridges of two consecutive teeth, the 
ridge running backwards from the main cusp of the anterior tooth and the ridge 
running forwards from the main cusp of the posterior tooth. 

The crowns of the lower gomphodont teeth of Diademodon were similar to those of 
the upper. Each had an external main cusp from which a ridge ran backwards, 
supporting one or two cusps which became smaller towards the back. A weak ridge 
ran forwards from the main cusp to terminate in a prominent cusp on the antero- 
external edge of the crown. A prominent cusp was present on the middle of the 
internal edge of the crown connected with the base of the main cusp by a ridge 
running transversely across the crown. Ridges supporting smaller cuspules radiated 
medially from the main cusp. A series of cusps was present on the anterior edge of 
the crown, from each of which a ridge ran backwards; they became bigger towards 
the mid-line. The central region of the crown was relatively high and flat. 

The unworn crowns appear to have been capable of crushing and puncturing food 
and it seems that the details of the crown pattern were quickly worn away in most 
Diademodon specimens. The enamel of Diademodon postcanines was extremely thin. 
The external main cusp of the lowers pounded into the basin formed between two 
adjoining upper postcanines (Figs 3C & 14) and, as wear proceeded, insignificant 
vertical shearing planes (Sh.s.) were developed between the external surface of the 
lower cusp and the internal surfaces of the ridges running forwards and backwards 
from the external main cusps of two adjoining upper teeth (Figs 3B & 14). As the 
external main cusps were worn down, these planes were lost and the anterior gom- 
phodont teeth were reduced to featureless nubbins of dentine. In several primitive 
mammals, e.g. Eozostrodon and Tinodon (Crompton & Jenkins, 1967, 1968), occlusal 
planes were established by destroying major features of the crown. 

The gomphodont postcanine teeth of Diademodon were followed by a series of 
three or four teeth which became progressively more sectorial towards the back, 
that is, the inner extension of the crown became progressively smaller. During 
occlusion the main cusp of the first semi-gomphodont lower tooth met the crown of 
the matching semi-gomphodont upper tooth internal to the main cusp of the latter 
and slightly behind the gap between the last gomphodont tooth and first semi- 
gomphodont tooth. The occlusal details of the posterior postcanines are illustrated 
in crown view in Fig. 3C and in internal view in Fig. 3D. As the lower jaw closed, 
shearing was possible between the outer surface of the main cusp of the lower semi- 


CYNODONTS AND TRITYLODONTIDS 39 


gomphodont tooth and the inner surface of the main cusp of the upper. However, 
as the tip of the main cusp of the lower tooth abutted against the occlusal surface of 
the internal extension of the corresponding upper cusp, it was rapidly worn down and 
its shearing function reduced. In the more advanced traversodonts the lower jaw 
was pulled backwards as the teeth came into occlusion; this postero-dorsally directed 
power stroke may have been initiated in Diademodon. 

The postcanine dentition of Diademodon showed a significant advance beyond the 
galesaurid condition.! The lower teeth lay directly below the crowns of the upper 
rather than internal to them. The cusps of upper and lower postcanines could 
therefore be used more effectively for puncturing and crushing food. In addition, 
matching vertical shearing surfaces were present on both the gomphodont series and 
the sectorial series of postcanine teeth; these were rapidly obliterated by wear but 
this was compensated for by the type of tooth replacement present in Diademodon 
which ensured that new gomphodont and sectorial teeth either replaced existing 
teeth at the back of the row or were added thereto. The gomphodont postcanines of 
Diademodon may be derived from those of early galesaurids or procynosuchids by 
widening the teeth in a lingual direction. The Lower Triassic cynodonts Pascual- 
gnathus and Andescynodon recently discovered in South America by Bonaparte 
(1967b) may throw considerable light on the evolution ot the Diadeimodon type of 
postcanine tooth from those of earlier cynodonts. 

The postcanine teeth of Tvivachodon of the South African Lower Trias and of 
Cricodon of the East African Middle Trias were slightly different from those of 
Diademodon. The postcanine row consisted of six or seven transversely ovate 
gomphodont teeth with two or three sectorial teeth behind. There was a sharp 
break between these two series; the transitional zone present in Diademodon, where 
the teeth become progressively more sectorial towards the back, was absent. The 
upper and lower gomphodont teeth in Tvivachodon (Fig. 14) and Cricodon (Fig. 3E 
and Plate 3) had three main cusps, an external, a central and an internal arranged 
to form a prominent transverse ridge across the crown. The anterior and posterior 
margins of the crown each bore a row of small cusps. The faint ridges which ran 
forwards and backwards from the external and internal main cusps of the uppers 
were not worn by the lowers to produce the vertical shearing surface seen in Diade- 
modon ; some degree of shearing may have been present between the sectorial teeth, 
but these were so small in comparison with the gomphodont teeth that it could not 
have been significant. The gomphodont teeth were presumably used to puncture 
and crush. The transverse ridges of the upper and lower teeth alternated with one 
another during occlusion but the wear facets suggest that they could not have 
sheared effectively. 


1} have assumed that Diademodon was derived from a galesaurid similar to Thvinavodon. This 
assumption is based upon the similarity of the sectorial teeth of Diademodon to the teeth of Thrinaxadon 
and upon the anteroposterior alignment of the cusps on the external edge of the upper teeth of Diademo- 
don. It is based also on the fact that galesaurids were the dominant cynodonts of the Lystvosaurus 
zone and that as a family they represent a distinct advance over the procynosuchids of the earlier 
Kistecephalus zone. However, some or all of the gomphodont cynodonts may have arisen directly from 
the Procynosuchidae (Bonaparte, 1963); this would explain the single external cusp on the gomphodont 
teeth of the Trirachodontidae. 


40 POSTCANINE OCCLUSION 


In the Trirachodontidae there was no alternate tooth replacement and, as in 
Diademodon, new gomphodont teeth were added behind to replace sectorial teeth. 


IV. POSTCANINE DENTITION OF THE TRAVERSODONTIDAE 


Until recently relatively little was known about Middle to Late Triassic therapsids 
(Crompton 1955, 1963B); recent work in South America, South Africa and East 
Africa, however, has led to the discovery of numerous therapsid remains, most of 
which have still to be described. It is now clear that the gomphodont cynodonts of 
the family Traversodontidae were the dominant cynodonts during the Middle Trias 
and early part of the Late Trias. The basic pattern of the crowns of the postcanine 
teeth of the traversodontids is characteristic of the group and separates it very 
clearly from the earlier gomphodont cynodonts. Relatively minor differences in the 
dentition and occlusal relations distinguish the genera of traversodontid cynodonts 
from each other, the structure of the postcanines providing a useful key for identify- 
ing genera and species and for determining the relationships and evolutionary history 
of the group. Like those of diademodontids, the postcanines of traversodontids 
were subjected to severe wear which in most cases eventually obliterated all details 
of the crown pattern. It will be shown below that the wear of the crowns of 
traversodontid postcanines resulted from a combination of complex occlusal relation- 
ships and jaw movements. The occlusion of traversodontid postcanines closely 
paralleled that of primitive mammals with tribosphenic molars. The abundance 
and diversity of traversodontids during Middle Triassic times may have been partly 
due to their highly evolved masticatory apparatus. 

In an earlier paper (Crompton 1955) three new genera of cynodonts (Scalenodon, 
Cricodon and Aleodon) and several indeterminate remains were described from the 
Manda Formation of Tanzania. No attempt was made to classify them above the 
generic level. Romer (1967) has recently revised the classification of gomphodont 
cynodonts; it is now apparent that Scalenodon angustifrons and the isolated maxilla 
with two teeth which I compared with the South American genus Gomphodontosuchus 
should both be included in the family Traversodontidae, while Aleodon brachyrham- 
phus is clearly not a traversodontid and Cvicodon metabolus appears to have been a 
surviving member of the Trirachodontidae. This accords with a view expressed by 
Bonaparte (1963). Subsequently Brink (1963a) described a gomphodont, Luangwa 
drysdalli, from the Ntawere Formation of Zambia; it is not well preserved and the 
occlusal aspects of the teeth are not known, but it appears to have been closely 
related to Scalenodon angustifrons, if not actually identical. In 1963 the British 
Museum (Natural History)—University of London Joint Palaeontological Expedi- 
tion (Attridge, Ball, Charig & Cox, 1964) collected additional material from the 
Ntawere Formation of Zambia and the Manda Formation of Tanzania; at least one 
new genus and two new species of traversodontid cynodonts were discovered as well | 
as additional specimens of Scalenodon angustifrons and Aleodon brachyrhamphus. I 
hope to give a full description of this new material in a later publication. Mean- 
while, because the postcanine teeth of all the East African traversodontids (including 
the new material) are discussed below, the new specimens have been named and 
briefly described in order to avoid future confusion. 


CYNODONTS AND TRITYLODONTIDS 41 


1. Description of three new species of Scalenodon 
from the Middle Trias of East Africa 


Family TRAVERSODONTIDAE von Huene 1936 
Genus SCALENODON Crompton 1955 


TypeE-sPecies. Trivachodon angustifrons Parrington 1946. 

Since I first described Scalenodon (Crompton 1955 : 647) other genera have been 
discovered in East Africa, South Africa and South America which are closely related 
to it. Because of this the original diagnosis given for Scalenodon is no longer 
applicable, several of the supposedly diagnostic features mentioned having sub- 
sequently proved to be diagnostic of the family Traversodontidae as a whole rather 
than of the genus Scalenodon in particular. A revised diagnosis for Scalenodon is 
therefore given below. 

This diagnosis is based entirely upon the characters of the upper postcanine 
teeth; it does not include features of the lower postcanine dentition because the 
latter is not known in all species of the genus. A detailed description of the rest of 
the skulls and skeletons of the several species of Scalenodon is now projected; this 
may necessitate some revision of the classification suggested in this paper. 


DiacGnosis. Small to medium-sized traversodontid cynodonts in which the upper 
postcanine teeth are transversely ovate; the external margin of the crown is gently 
convex; two main cusps are present (external and internal), the latter lying at the 
internal end of a prominent transverse ridge which usually supports an additional 
(central) cusp; small antero-external and antero-internal cusps are occasionally 
present; the inner surfaces of the external cusps form a vertical, antero-posteriorly 
aligned shearing surface, towards which the accessory cusp does not contribute 
substantially (contrast South American traversodontids); anterior and posterior 
cingula are present ; during the power stroke of occlusion the backward movement of 
the lower jaw was limited so that matching transverse ridges, upper and lower, were 
never drawn across one another. 

ComMENts. The upper postcanines of the four species of Scalenodon show some 
striking similarities to those of various genera of traversodontid cynodonts from 
South America. The type-material from both continents is at present being studied 
in order to determine, if possible, whether those similarities are due merely to con- 
vergence or to a closer phylogenetic relationship than is indicated by the present 
classification. 

S. angustifrons (Parrington). Material of this species includes not only the holo- 
type (Cambridge University Museum of Zoology, Ruhuhu Field Catalogue no. 120B) 
but also a number of other specimens which I referred to it when proposing the genus 
(Crompton 1955). Details of horizon and localities are given and discussed in the 
same work. Now that three new species of Scalenodon have been recognized (see 
below) it is possible to give a specific diagnosis for S. angustifrons. The diagnostic 
characters of all four species are compared in Table 1. Note also that in S. angirsti- 
Jrons there is a ridge of small cuspules on the outer surface of the main cusp of the 
upper postcanines. 


POSTCANINE OCCLUSION 


42 


pedojeaep Aj100d 


[[@M Ior1ezue 
o}epidsno-u0u 
surioy ‘podojeaep [jam 


[7eM Ior1ozue YSsy 
Aq peyoeuuod ‘a81e] yA0q 


yuesqe oq 0} 
sieodde dsno je1}u99 
‘UMOIO JO O8pa 

Ior1e}sod jo y1ed sur0F 
jerered 


A]Ysnor suIsieur 
Iotio}sod pure rIoreyue 


anbrjqo Aaa 


uMouyun 


ge1 


UsIADYI “S 


MmosyIsSAry *S 
Ul UeYy} yUoUTUIOId 
sso] nq pedojeasp |[JemM 


souturojsod 

Ior19}sod ur [yea 

Joliejue 9}eprdsno 
sul1oy podoyeAep [jam 


as81e] [eUIS}UI 
‘]]eUuIS [PUIE}x9 


sdsno 

[e1}ue9 pure [eure}xe 

sjtoddns ‘uorjztsod 
UI Io110}sod 910 [14S 


Jo}no ueyy 
JopIA UOTSeI IoUUT 


anbijqo 


Ajiorsieysod our|-prur 
wio1y APMP SUTAINO 


yol 


1aspUyD °S 


pedoyjeasp [Jom 


pedoyjeaesp [jam 


jyuesoi1d 


sdsno ye1}Ue0 pue [eure 


-xo szioddns ‘1aMoy 


‘SUOA{YSNSUD *S Ul ULY} 
uorisod ur ror1e3sod o10ul 


SUOALYSNSUD “S$ UI 
uey} IepnsuezeI s10Ur 


enbijqo jou 


oul[-prut 
0} JeTvered Ayreou 


vl 


WMoOsYyIsAYy *S 


I alavy 


pedojeasp Ay100d 


pedojasep Aj1ood 


yuesqe 


sdsno [e1} W989 pue [eUuIe} 


-xo sjioddns ‘sjjem 

Ior1eysod pur ror1ezue 

deozs YIM YstY 
“y}00} FO a[ppruz puryeq 


Iojno uey} IopIM 
I9AOU WOTSEI IOUUT 


enbiyqo jou 


Ajiori1e}sod out[-prut 
wor Aeme SUTAINO 


ar 


SUOALYSNSUD *S 


:wInpNsuro Io1103sod 


:UIN[NSUIO IOLIeZUe 


:sdsno 
Aiossao0e IOTIE}Ue 
[eUrIe}UI pue [euIE}xo 


!OSPII OSIOASUeIL 


1 MOTA 
UMOIO UI 4490} 
yuopoyduros jo odeys 
:e][IXeUL 
UL 399} JO SurzZesS 


: MOI-Y}.004 
jo uorztsod 


:oInsy-}xoL 


CYNODONTS AND TRITYLODONTIDS 43 


Scalenodon hirschsoni sp. nov. 
Plate 5; Text-figs 7-9 


DERIVATION OF NAME. In honour of Dr B. Hirschson, who was a member of the 
British Museum (Natural History)—-University of London Joint Palaeontological 
Expedition to Northern Rhodesia and Tanganyika, 1963, and who has done so much 
to help vertebrate palaeontologists and archaeologists working in southern Africa. 

MaTERIAL. Only the holotype in the British Museum (Natural History), Pal. 
Dept. regd. no. R. 8577. Field catalogue no. U12/3/26. Partial skull with well- 
preserved postcanine teeth. 


Horizon. Manda Formation (Middle Trias, probably Anisian). 


Locatity. Ruhuhu Valley, $.W. Tanzania: Locality U1r2 of the B.M.(N.H.)— 
University of London Joint Expedition, 1963. Between the Hiasi and Nijalila 
streams, just south of the Rutukira River; the most northerly of the Expedition’s 
localities west of the Njalila. 

DEscripTIon. See Table 1 for diagnostic characters. Note also that the incisors 
and canines, both upper and lower, are procumbent. The postcanines are described 
in greater detail on p. 49. 


Scalenodon attridgei sp. nov. 
Plate 6; Text-figs 10A, B 


DERIVATION OF NAME. In honour of Mr John Attridge, of Birkbeck College, 
London, who was a member of the British Museum (Natural History)—University 
of London Joint Palaeontological Expedition to Northern Rhodesia and Tanganyika, 
1963, and who made many of the discoveries of that expedition, including the unique 
specimen of this species. 

MATERIAL. Only the holotype in the British Museum (Natural History), Pal. 
Dept. regd. no. R. 8578. Field catalogue no. U2/z. A beautifully preserved snout 
with complete upper dentition; probably a young individual. 

Horizon. Manda Formation (Middle Trias, probably Anisian). 

Locatity. Ruhuhu Valley, S.W. Tanzania; Locality U2 of the B.M.(N.H.)— 
University of London Joint Expedition, 1963. Immediately next to the Peramiho- 
Litumba dirt road, on its left (south-western) side; low in the K8, before the Expedi- 
tion’s turn-off to Njalila and Mkongoleko, and probably only about a mile before 
the K7 boundary. 

Description. See Table 1 for diagnostic characters. Note also that the anterior 
edge of the unworn crown of the upper postcanines bears a row of five distinct cusps, 
of which the innermost is the largest. The postcanines are described in greater 
detail on p. 53. 

B 


44 POSTCANINE OCCLUSION 


Scalenodon charigi sp. nov. 
Text-fig. 10C 


DERIVATION OF NAME. In honour of Dr Alan J. Charig, Curator of Fossil Reptiles 
in the British Museum (Natural History), who initiated and participated in the 
B.M.(N.H.)—University of London Joint Palaeontological Expedition to Northern 
Rhodesia and Tanganyika in 1963. 

MATERIAL. Only the holotype in the Cambridge University Museum of Zoology, 
Ruhuhu Field Catalogue no. 136. Part of a left maxilla in which two postcanine 
teeth are preserved. 


Horizon. Manda Formation (Middle Trias, probably Anisian). 


Locatity. Ruhuhu Valley, S.W. Tanzania; Locality B26 of Stockley (1932 : 
620). Gingama, south of the Ruhuhu River. 


DESCRIPTION. See Table 1 for diagnostic characters. Note also that the central 
main cusp of the upper postcanines appears to be absent (this part of the tooth is 
damaged). 

ComMMENTS. This specimen was described and figured by Crompton (1955: 
659-660, fig. 14E), who compared it with the Brazilian species Gomphodontosuchus 
brasiliensis. It is now clear that its postcanine teeth are distinct from those of the 
other Ruhuhu traversodontids; the antero-external and internal accessory cusps are 
better developed than in the other East African forms, the antero-external forming 
part of a vertical shearing surface. It is therefore desirable, despite the smallness of 
the preserved portion, to base a new species on this specimen. 

S. charigi is similar in some respects to Gomphodontosuchus brasiliensis but is 
nevertheless distinct from that too. The postcanine teeth, though smaller, closely 
resemble those of the South American genera Exaeretodon and Gomphodontosuchus; 
the matching transverse ridges, however, did not cross one another during the power 
stroke of occlusion as they did in Exaeretodon and Massetognathus. 


2. Occlusion and jaw movements in the primitive 
traversodontid Scalendon angustifrons 


The most primitive traversodontid postcanines known are those of Scalenodon 
angustifrons.2 Although the dentition of this species has been described in detail 
(Crompton 1955), the new material discovered by the 1963 Joint Expedition has 
revealed many features of the postcanines and their occlusion which were not dealt 
with before. 


Fig. 4 shows three views of typical upper and lower postcanines of S. angustifrons; 
stereo-photographs are given in Plate 4. 


2Tf Andescynodon and Pascualgnathus described by Bonaparte (1966, 19676) are considered as traver- 
sodontids, then these should be regarded as the most primittve members of the family. I, however, 
should prefer to place them in the Diademodontidae. 


CYNODONTS AND TRITYLODONTIDS 45 


Upper teeth. These consisted essentially of three cusps arranged to form a 
transverse row, the central cusp being nearer the inner side of the crown. The 
internal (i.c.u.) and central (c.c.u.) cusps formed a high, prominent transverse ridge 
(t.r.) with anterior and posterior surfaces nearly vertical; a deep embayment (e.) 
separated this ridge from the external cusp (e.c.u.). A sharp ridge (a.r.) running 
forwards from the apex of the external cusp had a nearly vertical inner face which 
formed the outer border of a deep valley (a.v.) in the anterior surface of the tooth, 


ANTERIOR 


lcm EXTERNAL 


Fic. 4. Scalenodon angustifrons. Postcanine teeth. A. Posterior view of upper. 
B. Posterior view of lower. C. Crown view of upper. D. Anterior view of upper. 
E. Anterior view of lower. F. Crown view of lower. For key to abbreviations see p.69 


46 POSTCANINE OCCLUSION 


immediately in front of the embayment between the external and central cusp (see 
Fig. 4D). Asmaller, less well defined valley (p.v.) occupied a corresponding position 
behind the transverse ridge. The anterior valley of one postcanine and the posterior 
valley of the preceding tooth together formed a deep occlusal basin with high antero- 
posteriorly aligned shearing surfaces. 

Lower teeth. The crown of a lower postcanine of S. angustifrons consisted of 
two high anterior cusps, the external (e.c.l.) being higher than the internal (i.c.l.); a 
high ridge ran backwards along the outer surface of the crown (p.r.) from the apex 
of the external cusp, its outer surface being more or less vertical. The external and 
internal cusps were connected by a transverse ridge which dipped down to a saddle 
between them; the anterior surface of this ridge was nearly vertical. A deep basin 
(b.1.) lay behind the two main cusps, rimmed posteriorly by a row of small cuspules 
of which the outermost (p.a.c.) was the largest. A small anterior accessory cusp 
(a.a.c.l.) was present on the anterior surface of the crown. 

OccLusion. In Fig. 6 several opposing postcanines are shown in crown view and 
oblique internal view at the beginning of dynamic occlusion (A, B, respectively) 
and at the end (C, D). At the beginning of dynamic occlusion the anterior surface 
of the transverse ridge formed by the two main cusps of the lower tooth sheared past 
the posterior surface of the transverse ridge formed by the central and internal main 
cusps of the preceding upper tooth. (In Fig. 6B lower postcanine 6 is shearing 


Fic. 5. Scalenodon angustifrons. Lateral views of postcanine teeth, showing the postero- 
dorsal direction of the power stroke. A. At the beginning of dynamic occlusion. 
B. At the end of dynamic occlusion. 


CYNODONTS AND TRITYLODONTIDS 47 


against upper postcanine 5). This produced wear facets on the front of the trans- 
verse ridge of the lowers and on the back of the transverse ridge of the uppers. The 
central cusp of the upper tooth fitted into a groove on the anterior surface of the 
lower tooth between the two main cusps. The outer surface of the external main 
cusp of the lower tooth sheared past the posterior portion of the vertical internal 
surface of the external main cusp of the preceding upper postcanine; the position of 
the postcanines at the beginning of dynamic occlusion as seen in lateral view is given 
in Fig. 5A, which shows the resulting striations (w.f.) on the outer surface of the 
external main cusp of the lowers. As the jaws continued to close (Figs 5B and 6D) 
the lower jaw moved slightly backwards rs well as upwards so that the external 
surface of the lowers sheared past the anterior portion of the vertical internal surface 
of the external cusp of the corresponding upper postcanine tooth. The arrows in 


EXTERNAL S 6 i 


ANTERIOR 


lcm 


Fic. 6. Scalenodon angustifrons. Details of tooth occlusion. The numbers 4 to 7 
indicate the positions of the teeth in the postcanine series. A. Crown views of the 
postcanines at the beginning of dynamic occlusion, with upper and lowers superimposed. 
B. Oblique internal view of the same. The heavy arrow indicates the passage of the 
tip of the internal main cusp of the lower teeth during dynamic occlusion. C. Crown 
views of the postcanines at the end of dynamic occlusion, with uppers and lowers super- 
imposed. The main transverse and longitudinal shearing surfaces are drawn in heavy 
lines. D. Oblique internal view of the same. For key to abbreviations see p. 69. 


48 POSTCANINE OCCLUSION 


Figs 6B and 5A indicate the direction of movement of a single lower postcanine 
during the final stages (‘“power stroke’’) of occlusion. The posterior surface of the 
external cusp of the lower tooth and the anterior surface of the external cusp of the 
corresponding upper formed two opposing crescents when seen in lateral view 
(Fig. 5A). Such an arrangement is ideal for cutting provided that the lower jaws 
moved slightly backwards during occlusion. An analogous arrangement typified 
the shearing surfaces of tribosphenic molars (Crompton & Hiiemae, 1969b). When 
the postcanines of S. angustifrons were in tight occlusion (Fig. 6, C and D) the 
external main cusp of a lower postcanine lay in the valley (Fig. 4D, a.v.) in the 
anterior surface of the corresponding upper postcanine and the central cusp of the 
upper lay above the posterior basin of the lower. The dentition of S. angustifrons 
was characterized also by the addition of new gomphodont teeth with shearing 
surfaces behind and by the loss of worn postcanines in front. The replacement 
pattern was similar to but simpler than that of Diademodon. 

The occlusal pattern of S. angustifrons represented a distinct advance over that of 
Diademodon. Not only were transversely orientated shearing planes added, but the 
occlusal basin of the upper postcanines was considerably deepened by the develop- 
ment of deep valleys immediately internal to the external main cusp. Consequently 
the tip of the main cusp of the lower postcanine was not worn down as rapidly as it 
was in Diademodon, where it abutted directly against the crown surface of the 
occluding tooth. Deepening the occlusal basin also increased the height of the 
shearing surfaces. 

The postcanines of S. angustifrons therefore consisted essentially of a series of 
transversely and longitudinally orientated shearing planes. The positions of these 
shearing planes on upper and lower postcanines are indicated by heavy lines on 
Fig. 6C. Occlusion in other traversodontid cynodonts and tritylodontids was 
basically a modification of the arrangement that was present in Scalenodon angusti- 
frons. The tips of the cusps were used for puncturing, the sides of several of the 
cusps for shearing and the posterior heel of the lower posterior postcanines provided a 
firm basin for crushing, analogous to the talonid basin of the tribosphenic molar. 
The potscanines of S. angustifrons were therefore functionally similar to the tribo- 
sphenic molars of primitive mammals. In mammals with tribosphenic molars and 
in some of the insectivores and herbivores with more specialized molars the jaw 
moves not only vertically during occlusion but also transversely and forwards in 
order to utilize a series of shearing plates. In S. angustifrons the mandible moved 
vertically and slightly posteriorly during occlusion and thereby also utilized a series 
of shearing planes. 

It is generally assumed that in primitive cynodonts the tympanic membrane was 
partially attached to the posterior surface of the quadrate (see Hopson, 1966 for a 
complete review of this problem). The posterior movement of the jaw during 
dynamic occlusion in S. angustifrons was apparently too great to be accommodated 
within the available space between the glenoid of the articular and the condyle of the 
quadrate. Parrington (1946) suggested that in Thvinaxodon and later cynodonts the 
quadrate itself must have been capable of antero-posterior movement but recognized 
that such movement would have torn or stretched the small tympanic membrane 


CYNODONTS AND TRITYLODONTIDS 49 


because the stapes rested against the quadrate. In a new skull of S. angustifrons 
(B.M.(N.H.) R. 8579), discovered in 1963 in Tanzania, it can be seen that the quad- 
rate was held in a groove in the squamosal and could slide both downwards and 
forwards; the amount of movement of which it was capable appears to have been 
sufficient to have allowed the mandible to be pulled backwards a little during the 
final stages of dental occlusion. Kemp (1969), following on the earlier work of 
Parrington (1955), has shown that the quadrate was extremely mobile in gorgon- 
opsians too so that, despite the firm junction between the articular and the quadrate, 
the mandible was capable of antero-posterior movements during mastication; a 
mobile quadrate was presumably present in all cynodonts and therocephalians. In 
S. angustifrons the external auditory meatus presumably lay in a groove of the 
squamosal and, as Parrington (1946) has shown, the groove was terminated by a 
semicircular lip which supported the tympanic membrane without involving the 
posterior surface of the quadrate. Movement of the quadrate would therefore not 
have involved the tympanic membrane directly, but this does not solve the problem 
completely as the stapes was presumably in contact with both tympanic membrane 
and quadrate, and stapes and quadrate may have moved together. Unfortunately 
the relationship between the stapes and the quadrate of advanced cynodonts is not 
well known, but the removal of the tympanic membrane contact from the quadrate 
to the squamosal in primitive traversodontids may be related to the antero-posterior 
movements of the mandible which appear to have taken place during occlusion. 

The postcanine tooth rows of S. angustifrons diverged backwards. Consequently 
antero-posteriorly aligned cutting surfaces of opposing teeth would have tended to 
separate during extensive backward movement of the lower jaw and for this reason 
the amount of antero-posterior movement during occlusion in S. angustifrons was 
probably small. It is doubtful whether the jaw could have swung far enough 
laterally to retain contact on one side. A mobile mandibular symphysis would have 
overcome this limitation, but the nature of the fossil material suggests that the two 
rami were firmly united. The fossilized remains of S. angustifrons consist of 
numerous fragments, indicating that the skeletons of this animal were usually 
scattered and broken before fossilization; despite this the mandibular rami are 
usually found fused at the symphysis, as would not be expected had the symphysis 
been mobile during life. By contrast, the mandibular rami of tritylodontids and 
early mammals are seldom if ever preserved fused at the symphysis, which suggests 
that the latter was mobile. Szalay (1969) has argued that primitive primates too 
had a mobile symphysis because Palaeocene primate mandibles are usually preserved 
separated. 


3. Occlusion and jaw movements in Scalenodon hirschsoni 


The only known specimen of S. hivschsont is ideal for the study of occlusion because 
it yielded to preparation with acetic acid; the lower jaw was thereby freed from the 
remainder of the skull. It was possible to study details of the structure of the teeth, 
the wear facets and occlusal relationships. Among the features of this species which 
clearly separate it from S. angustifrons are that the upper incisors and lower canines 


50 POSTCANINE OCCLUSION 


are slightly procumbent and that the postcanine rows are nearly parallel to one 
another, the last postcanine lying immediately in front of the transverse process of 
the pterygoid. The basic structure of the crowns of the postcanines (Figs 7A, B, 8; 
Plate 5) is essentially the same as that of S. angustifrons. The crowns of the upper 
postcanines are relatively longer antero-posteriorly than those of S. angustifrons and 
the portion of the crown lying in front of the transverse ridge is considerably wider 


1.€.U. 


ANTERIOR 


EXTERNAL 


Icom 


Fic. 7. Scalenodon hirschsoni sp. nov. Postcanine teeth. A. Crown view of upper. 
B. Crown view of lower. C. Crown views of uppers and lowers superimposed to show 
the relative positions at the beginning of dynamic occlusion. D. The same, at the end 
of dynamic occlusion. 


| 
| 


| 


CYNODONTS AND TRITYLODONTIDS 51 


than the portion behind; this is probably due more to addition to the anterior part 
of the crown than to a posterior migration of the transverse ridge because small 
additional cusps (a.a.c.u.) are present on the ridges running forwards from both 
external and internal main cusps. The embayment between the external and 
central main cusps (Fig. 8A) is deeper than that of S. angustifrons and the transverse 
ridge is not as high as in the latter species. A fairly prominent posterior cingulum 
(Fig. 7A, p.c.) is present. 

In the lower postcanines (Fig. 7B) the transverse ridge formed by the two maiu 
cusps is not as high as that of S. angustifrons and the anterior accessory cusp (a.a.c.].) 
islarger. Details of occlusion and of the amount of longitudinal movement during 
mastication are illustrated in Figs 7C—D, 8A—D and 9A-E. Because the transverse 
ridge of the uppers also is lower than in S. angustifrons and because it was apparently 
worn down fairly rapidly, its posterior surface does not form a high wall (see internal 
views of beginning and end of dynamic occlusion, Fig. 8C—D); nevertheless small 
matching wear facets on that surface and on the anterior surface of the transverse 
ridge of the lower postcanines indicate that some shearing took place in this position. 
The mandibular movements which probably took place during occlusion have been 
reconstructed by manipulating the opposing jaws and by studying the striations on 
the wear facets of opposing teeth. These movements are illustrated in Fig. 9 in 
external view by showing several positions of the lower postcanines 5 and 6 relative 
to the upper postcanines 4 and 5. As the jaws closed, the anterior part of the 
external surface of the main cusps of lowers 5 and 6 sheared past the internal surfaces 
of the external main cusps of uppers 4.and 5 (Fig. gA—B). As the mandible proceeded 
backwards (Fig. 9B—C—D) the external surface of the external main cusp of lower 
postcanine 5 sheared past the internal surface of the external main cusp of upper 
postcanine 5. This shear, as it would have appeared in internal view, is illustrated 
in Fig. 8C-D. The wear facets on the external surface of the lower postcanines 
resulting from this backward movement are shown in Fig. 9F. The important 
point is that at the beginning of dynamic occlusion the transverse ridge of the 5th 
lower postcanine lay behind the transverse ridge of the 4th upper postcanine (Fig. 
7C). In essence, therefore, occlusion resulted from a posterior and a vertical jaw 
movement, just as in S. angustifrons. However, a lightly worn 5th lower postcanine 
of S. hirschsom shows a distinct wear facet (Fig. 7B, p.w.f.) on the posterior surface 


_ of the main cusp; this matches a wear facet on the anterior surface of the transverse 


ridge of the 5th postcanine. It is difficult to account for these facets if the power 
stroke of the lower jaw was directed dorso-posteriorly. Admittedly they could have 
resulted from the postero-dorsal surface of the transverse ridge of the lower tooth 
being drawn backwards and downwards across the antero-ventral surface of the 
transverse ridge of the upper. This movement, as it would appear in external view, 
is shown in Fig. gD. Although this would have involved crushing between the 
opposing transverse ridges, it would have required that the lower postcanines be 


_ dragged down an inclined plane. The same wear facets, however, would have been 


formed if the mandible had moved forwards and upwards during dynamic occlusion 
as shown in Fig. 9E so that the leading edge of the transverse ridge of the lowers 
sheared past the trailing edge of the transverse ridge of the uppers. This movement 


POSTCANINE OCCLUSION 


lom 


Fic. 8. Scalenodon hivschsoni sp. nov. Postcanine teeth. A. Posterior view at the 
beginning of dynamic occlusion. B. Posterior view at the end of dynamic occlusion. 
C. Oblique internal view at the beginning of dynamic occlusion. D. Oblique internal 
view at the end of dynamic occlusion. E. Sagittal section through part of opposing 
postcanines to show matching shearing surfaces resulting from anteriorly directed power 
stroke. F. Internal view of lower postcanine to show wear facet resulting from 
anteriorly directed power stroke. 


CYNODONTS AND TRITYLODONTIDS 53 


as it would appear if a longitudinal section were cut through the teeth, is shown in 
Fig. 8E; the enamel-like material (en.) is considerably thicker on the anterior surface 
of the transverse ridge of the lower tooth than on the occlusal surface or in the 
posterior basin, just as would be expected if this species were capable of a forwardly 
directed power stroke as well as the usual backwardly directed stroke. 


4. Postcanine dentition of Scalenodon attridgei 


This species is known only from an isolated snout, with the upper teeth well 
preserved on both sides. The postcanine row (Fig. 10A, B, Plate 6) of eight teeth 
ends behind in three teeth which become progressively smaller, as in many specimens 
of S. angustifrons. The first five teeth are so worn that most of the details of crown 
structure are lost, but the 6th and 7th postcanines are only slightly worn and the 8th 
not at all. Although the last two teeth are smaller than the more anterior ones and 
would presumably have been replaced later in life by larger gomphodont teeth, they 
are of great interest. The basic pattern of the postcanines of S. attridgei is similar 
to that of S. angustifrons and S. hirschsoni. They are, however, set obliquely in the 
maxilla, and the internal surface is slightly wider than the external surface. The 


Fic. 9. Scalenodon hirschsoni sp. nov. Postcanine teeth. A-D. External views to show 
successive stages of the posteriorly directed power stroke. Heavy arrow in A indicates 
total extent of backward movement involved. E.D. The same, but to show anteriorly 


directed power stroke. F. External view of lower teeth to show wear facets on the 
external surfaces. 


54 POSTCANINE OCCLUSION 


important feature ot the upper postcanines of S. aftridgei is the presence of a row of 
well developed cuspules along the anterior border of the crown of postcanines 7 and 
8; in postcanines 5 and 6 they have been obliterated by wear. The antero-medial 
cuspule (a.a.c.u.) is the largest of these cuspules and they tend to become smaller 
towards the exterior (Fig. 10B). A high ridge joins the external main cusps to the 
most external cuspule of the anterior row. The central and internal main cusps 
(c.c.u. and i.c.u.) are both large and well differentiated and form the transverse 
ridge. A basin (b.u.) is present in the occlusal surface of the crown; this is bordered 
behind by the transverse ridge, in front by the anterior row of cuspules and externally 
by the vertical inner wall of the external main cusp. A deep valley separates the 
internal main cusp and the most internal cuspule of the anterior row (a.a.c.u.) so that 
the basin is completely surrounded except for this narrow valley opening internally. 
In the 7th postcanine the tips of the central and internal main cusps and the tips of 
the cuspule forming the anterior ridge are worn away. In the more anterior teeth 
wear has tended to obliterate the original details of the crown pattern and especially 
the anterior row of cuspules. The tips of the central and internal main cusps and the 
crest of the transverse ridge have been worn away so that the occlusal surface of the 
crown in front of the transverse ridge is a plane sloping slightly upwards in an antero- 
external direction; this is best seen in the anterior view of the upper postcanines 
(Fig. 10B). Except for two internal cuspules, most of the cuspules of the anterior 
row of the 6th postcanine have been worn away and only a low wall remains. A 
feature of the crown of the 5th and 6th postcanines which is not present in the smaller 
7th and 8th is a faint posterior ridge or cingulum (p.c.) close to the posterior margin 
ot the crown. A shallow valley which widens slightly towards the external side lies 
anterior to it; this will be referred to as the posterior basin (p.b.). The wide forward 
and upward sloping flat surfaces of the crowns of the upper postcanines of S. attridget 
could have resulted from both antero-dorsal and postero-dorsal power strokes. The 
postcanines of the Brazilian species Tvaversodon stahleckeri (von Huene 1944 : 48) 
are extremely worn, but from what remains of the upper teeth they appear to have 
been similar to those of S. attridgez. 


5. Postcanine dentition of Scalenodon charigt 


This specimen, consisting of an isolated maxilla with two posterior postcanines, 
was previously compared (Crompton, 1955) with the Brazilian species Gomphodonto- 
suchus brasiliensis. Although the teeth were badly damaged several details can 
still be seen, and, now that more traversodontids from South America and East 
Africa have been described and figured, additional comments may be made. 

The teeth (Fig. 10C) are set obliquely in the maxilla. The external anterior 


accessory cuspule (a.a.c.u.) is larger than in S. hivschsoni and the internal surfaces of © 


the two external cusps form a high shearing surface. The main transverse ridge is 
situated near the posterior edge of the crown. The central cusp appears to be absent. 
The anterior wall is high and is terminated internally by a high rounded cuspule 
(a.a.c.u.) ; consequently the anterior basin (b.u.) is deep and occupies most of the 
occlusal surface of the crown. The shearing surface on the internal face of the 


CYNODONTS AND TRITYLODONTIDS 55 


external cusp is continuous with that on the posterior surface of the anterior wall of 
the same tooth; this suggests that the anterior surface of the transverse ridge of the 
corresponding lower postcanine sheared up the anterior wall of the upper postcanine 
rather than across it. Although the anterior wall was present in S. attridgei, it was 


| cm 


lcm 


Fic. 10. A. Scalenodon attridgei sp. nov. Crown view of last four upper postcanines. 
B. Scalenodon attridgei sp. nov. Anterior views of the same. C. Scalenodon charigi 
sp.nov. Crown view of last two upper postcanines. For key to abbreviations see p. 69. 


56 POSTCANINE OCCLUSION 


rapidly worn away and apparently did not form a significant vertical shearing sur- 
face. The structure of the anterior wall, the absence of a central cusp and the 
oblique position of the crown relative to the longitudinal axis of the palate are 
reminiscent of the South American genus Exaeretodon. 


6. Occlusion and jaw movements in a species of Massetognathus 


The postcanines of the Argentine traversodontid Massetognathus pascuali have 
been described in detail by Romer (1967), but he does not discuss occlusion in detail. 
Dr. Bonaparte presented the Peabody Museum with a jaw fragment that has been 
tentatively assigned to the genus Massetognathus, and in which upper and lower 
postcanines were preserved in tight occlusion; the jaws have been carefully separated 
by Mr C. Schaff. Distinct wear facets are preserved on most of the teeth, and by 
matching upper and lower wear facets it has been possible to determine the jaw 
movements that must have taken place in Massetognathus during the final stages of 
the masticatory cycle. Although the postcanines are almost identical to those of 
M. pascuali the wear pattern is slightly different and the fragment should perhaps 
be placed in a different species or genus. This may be possible when the entire fauna 
of gomphodont cynodonts from Chafares is fully described. 

The postcanines (Fig. 11 & Plate 7) are very similar to those of S. angustifrons 
except that two accessory cuspules rather than one are present on the ridge leading 
forwards from the external main cusp, which latter lies further back than in S. 
angustifrons. A characteristic feature of Massetognathus and Exaeretodon not 
present in the African traversodontids is that the external margin of the upper post- 
canines as seen in crown view is drawn outwards and backwards (Fig. 11B) to forma 
distinct lobe. The transverse ridge is high and forms the posterior border of the 
crown, the posterior cingulum being but poorly developed. The inner surface of the 
external main cusp and of the two anterior accessory cuspules forms a high vertical 
wall which is more pronounced than in S. angustifrons. The point of junction 
between the transverse ridge and the external main cusp lies near the posterior 
border of the crown. The lower postcanines are similar in structure to those of S. 
hirschsont but lack the anterior accessory cuspules. As in all gomphodont cyno- 
donts the amount of wear increases progressively towards the front of the jaw. 
Matching shearing planes are shown in Fig. 11D & E. As the teeth came into 
occlusion the outer surface of the 4th lower postcanine (Fig. 11D) sheared past the 
internal surface of the external main cusp of the 3rd upper postcanine (wear facets 2 
in Fig. 11C, D & E); then, as the jaws continued to close, it also sheared past the 
inner surface of the two anterior accessory cuspules of the 4th upper postcanine (wear 
facets 1). The two facets, 2 and 1, on the 3rd and 4th upper postcanines respectively, 
are therefore continuous. This action was similar to that in Scalenodon. At the 
beginning of occlusion the tips of the two main cusps of the 4th lower postcanine lay 
anterior to the tips of the central and external main cusps of the 3rd upper post- 
canine, i.e. the transverse ridge of the lower lay in front of the transverse ridge of the 
upper (Fig. 14). The central cusp of the upper lay directly behind the valley 
separating the two lower cusps. Because of this, as the mandible was drawn back- 


Sif 


CYNODONTS AND TRITYLODONTIDS 


‘wOIsN{N00 ormeUAp jo Suruurseq oy} ye Ired Sutsoddo jo morta so110}Ss0g “YY 

‘soovjins Sureoys f sioddn omy Jo MorA uMOID “| 

Suryoyeur Moys 0} “IQMOT JO MOIA UMOID “CG 

‘ayO4s Iomod sy} Jo sasejs [euy oy} Sutmnp sioddn yj 0} oatyeIor 

Y}00} IoMo] & JO (Moxre Aavay) JUSUIEAOUI oY} PU 4003 10ddn 943 Jo sdsno [euIE}xe 

a4} JO SOP} [EUIN}UI 9Y} UO SBdvJINSs SuIIveYys oy} Jo yYZdep oy} MOYS 0} MOIA [eUIOZUT 

‘9 «xoddn uiom Aysis JO MoIA UMOID “q “IOMO] UIOM APYSI[S JO MorA UMOID “VW 
"y}09} euTUeOJsSOg + ‘(UInesnyY Apoqeeg efexX ut ueutoeds) ‘ds snyzwusojassppy “11 “DI 


fos hE Vv 


YOINSLNV 


58 POSTCANINE OCCLUSION 


wards and the lower cusps were dragged across the transverse ridge, pronounced 
wear facets were formed on either side of the central cusp of the uppers and on the 
tips of the main cusps of the lowers. These matching facets have been numbered 4 
and 5 in both uppers and lowers (Fig. 11, D & E). As the mandible was drawn 
further back the main cusps of each lower tooth carved grooves into the anterior wall 
of the succeeding upper tooth. These grooves have been numbered 6! and 7! on 
the upper tooth (Fig. rrE) and the matching shearing surfaces 6 and 7 on the lower 
tooth (Fig. 11D). It is clear from the orientation of these matching facets that they 
were produced by the backward and upward movement of the mandible during the 
final stages of the masticatory cycle. A study of the wear facets in this species of 
Massetognathus therefore suggests that, as in S. angustifrons, the jaws were drawn 
backwards during dynamic occlusion; but those facets which suggest an anteriorly 
directed power stroke in S. hirschsoni and S. attridget are absent in Massetognathus. 
Perhaps the most important feature of occlusion in this species of Massetognathus is 
that the transverse ridge of the lowers was drawn across the transverse ridge of the 
uppers. This was not the case in Massetognathus pascuali, S. angustifrons or S. 
hirschsoni, where the anterior surface of the transverse ridge of the lowers sheared up 
the posterior surface of the transverse ridge of the uppers. It is possible to derive 
the situation in the new species of Massetognathus from that in S. angustifrons simply 
by increasing the extent of the antero-posterior movement during occlusion. This 
is important when considering the ancestry of the tritylodontids. 


7. Postcanines of Exaeretodon and Gomphodontosuchus 


Bonaparte (1962) has described the teeth of Exaeretodon frenguelli; 1 was able to 
study postcanine teeth of this species in the Museum of Comparative Zoology at 
Harvard and at the Instituto Miguel Lillo in Tucuman. The upper postcanines 
(Fig. 12A, B, C) are similar to those of Massetognathus; and the postero-external 
extension of the external region is so marked that the tooth as seen in crown view 
may be divided into two lobes, a lateral and a medial. Well developed external 
(e.c.u.), anterior accessory (a.a.c.u.) and posterior accessory (p.a.c.) cusps are present 


on the external margin of the tooth; their internal surfaces form a continuous antero- | 


posteriorly aligned shearing surface which extends right along the tooth from front 
to back. The transverse ridge terminates short of the base of the external main 
cusp; its central cusp is absent. Two anterior accessory cusps (a.a.c.u.) are present, 
one internal and one external. In posterior view (Fig. 12C) it can be seen that the 
crest of the transverse ridge rises very sharply ventrally towards the tip of the 
internal main cusp. The anterior wall (a.w.) of Exaeretodon is a prominent feature; 
it can be seen in anterior view (Fig. 12B) that it too rises very sharply ventrally to 


terminate in the internal anterior accessory cusp. A shallow basin separates this: 


anterior wall from the transverse ridge. The cutting surface on the inner face of the 
external main cusp of each tooth is continuous with those in front and behind. 
Because the anterior wall and the transverse ridge of each upper postcanine lie 
obliquely the internal main cusp of each lower postcanine is considerably further 
back than the external (Fig. 12D). Mandibular movements during dynamic 


CYNODONTS AND TRITYLODONTIDS 59 


occlusion were probably similar to those of Massetognathus pascuali and Scalenodon 
angustifrons. Wear facets indicate that the transverse ridges of the upper and 
lower postcanines were not drawn across one another from front to back but it 
appears that, instead, the primitive transverse shear still took place between the 
anterior surface of the transverse ridge of the lower tooth and the posterior surface 
of the transverse ridge of the upper. There is no indication that there was a for- 
wardly directed power stroke. However it will not be possible to discuss jaw move- 
ments in Exaeretodon with any degree of confidence until the wear facets on the 
abundant postcanines have been studied. 

The lower postcanines of the southern African traversodontid Scalenodontotdes 
macrodontes Crompton & Ellenberger 1957 are almost identical in size and structure 
with those of Exaeretodon. Scalenodontoides was found in association with melanoro- 
saurid (prosauropod) dinosaurs and is therefore younger than the East African 
traversodontids. 

I have been unable to study the type of Gomphodontosuchus brasiliensis (von 
Huene 1944-48) and the following remarks are based upon stereophotographs 
of the specimen taken by Dr J. Hopson. This genus has exaggerated some of the 
features of the postcanines of Exaeretodon. The teeth are set in the jaw more 


qa.d.c.u. 


e.C.u. a.a.c.u. 


Fic. 12. Exaeretodon frenguelli. Typical postcanine teeth. A. Crown view of upper. 
B. Anterior view of upper. C. Posterior view of upper. D. Crown view of lower. 
For key to abbreviations see p. 69. 


60 POSTCANINE OCCLUSION 


obliquely so that the angle between the transverse ridge and the inner shearing 
surface of the external cusp is smaller than in Exaeretodon; the obliquity is reflected 
also in the outline of the crowns of the lower postcanines. In Gomphodontosuchus 
the anterior wall of the upper postcanine is higher than in Exaeretodon, the crown 
basin therefore deeper; this presumably indicates an increase in the cutting function 
of the anterior wall. 


V. DISTRIBUTION OF THE TRAVERSODONTIDAE 


Traversodontids are known to have existed for a long period of time and their 
dentitions indicate that they occupied several different ecological niches. At 
present they are known with certainty only from Africa and South America; indeed, 
this is true of all gomphodont cynodonts, and it has therefore been suggested that 
they were restricted to the southern continents. However, a large lower jaw of what 
may prove to be traversodontid cynodont was discovered in the Upper Triassic 
Wolfville Formation of the Newark Group in Nova Scotia by Dr R. L. Carroll and 
Dr D. Baird (Romer, 1967) ; unfortunately no postcanine teeth were preserved in situ, 
but the size of the jaw and the structure of the symphysis showed close similarity to 
Scalenodontoides macrodontes from southern Africa. 

The postcanine teeth of traversodontids from several horizons and numerous 
localities in Africa are remarkably similar to those of traversodontids from various 
localities in South America. Scalenodon angustifrons closely resembles Masseto- 
gnathus pascuali; S. charigi closely resembles Exaeretodon frenguelli and Gompho- 
dontosuchus brasiliensis; and S. attvidger closely resembles Tvaversodon stahleckeri. 
The traversodontids of the Chanares Formation (Massetognathus) are comparable in 
size to the various species of the East African Scalenodon, but, while no East African 
form approaches the gigantic size of the traversodontids from Ischigualasto (Exaere- 
todon, Proexaeretodon and Ischignathus), Scalenodontoides from southern Africa 
indicates that large gomphodont cynodonts were present on that continent during 
Late Triassic times. Unfortunately the traversodontids collected in Brazil (Colbert, 
1963) have not yet been described. No African site has been discovered which has | 
yielded traversodontids in anything like the abundance ot those of South America. | 

The similarity of the terrestrial Early Triassic faunas from Argentina recently 
described by Bonaparte (1967) and of terrestrial Middle Triassic faunas from various 
parts of South America to African faunas of corresponding age, including the 
cynodonts, may indicate a close connection—or at least easy migration routes— 
between Africa and South America during Triassic times. Recent views (Bullard 
1969, Menard 1969) on the relative positions of the continental masses of Africa and 
South America before the end of the Cretaceous suggest that they were extremely 
close, if not united, during the Trias. 

Early cynodonts (Late Permian to Early Triassic) are known from South America 
(Bonaparte, 1967a), South Africa (Haughton & Brink, 1954), East Africa (Parrington, 
1936), China (Young, 1961), and Russia (Tatarinov, 1968). A carnivorous cynodont 
of Early to Middle Triassic age probably occurs in China (Young, 1959). The descen- 
dants of the cynodonts, the tritylodontids, have been discovered in Late Triassic de- 


CYNODONTS AND TRITYLODONTIDS 61 


positsin South America (Sill, 1969), Africa (Fourie, 1968), China (Young, 1947), North 
America (Colbert, pers. comm.) and Europe (Kermack, 1965 and Kihne, 1956). 
Early mammals, also the descendants of cynodonts, have been discovered in the Late 
Triassic of southern Africa (Crompton, 1964), China (Rigney, 1963) and Europe 
(Kermack, 1965). In view of the world-wide distribution of these related groups it 
would not be expected that cynodonts should be totally absent from northern 
continents during Middle Triassic times. In particular, the gomphodont cynodonts 
may therefore have enjoyed a world-wide distribution; it may just be that their 
northern representatives (other than the jaw found by Carroll and Baird in Nova 
Scotia) have not been discovered as yet, and their apparent absence from northern 
continents may be due to the lack of suitable continental deposits of Middle Triassic 
age rather than to the absence of the animals themselves (Colbert, 1963). 

The distribution of other Middle Triassic groups tends to support this view. For 
example, several Middle Triassic archosaurs are known from southern continents 
(Charig, 1967), but only a few, almost accidental finds are all that is known of the 
archosaurs of this age from northern continents (Krebs, 1965). 


VI. OCCLUSION IN TRITYLODON AND THE ORIGIN OF THE TRITYLODONTIDAE 


Several features of the skull and dentition of the traversodontids suggest that a 
member of this family may have been ancestral to the tritylodontids. This sugges- 
tion, made originally by Crompton & Ellenberger in 1957, is supported by the new 
material The crowns of the upper cheek teeth of Tvitylodon (Fig. 13J) consist 
essentially of three longitudinal rows of crescent-shaped cusps, three cusps each in 
the internal and central rows and two cusps in the externalrow. The corresponding 
lowers (Fig. 13K) consist of two rows each of three crescent-shaped cusps. The 
crescent of the upper cusps are concave forwards, whereas the crescents of the lower 
cusps are concave backwards (Fig. 13L). The two rows of lower cusps occluded 
between the three rows of upper cusps. Wear facets bearing parallel striations are 
developed on both surfaces of all the cusps except the outer surface of the external 
cusps of the uppers and the inner surface of the internal cusps of the uppers, which 
do not face any other surface; they indicate that during mastication the jaws moved 
horizontally. The extent of movement during occlusion is shown in Figs 13L and 14. 
The lower postcanine commenced dynamic occlusion by making contact with the 
upper tooth one position further forward in the upper jaw. The anterior edges of the 


upper cusps and the posterior edges of the lower cusps formed a multiple cutting 


mechanism which would have been effective only if the power stroke during mastica- 
tion were directed backwards. Occlusion therefore involved the dragging of the tips 
of the central row of cusps of the upper teeth and of the tips of both rows of cusps of 
the lowers across the floors of the valleys between the longitudinal rows of cusps of 
the opposing teeth. Asa result these crescentic cusps were rapidly worn down, there- 
by decreasing the shearing action of their near-vertical surfaces. In many specimens 
of tritylodontids the crowns of the postcanine teeth consist of almost flat surfaces 
scarred by longitudinal grooves. The backward jaw movements during occlusion, 
the rapid wearing down of teeth, the eruption of new teeth at the back to provide 


POSTCANINE OCCLUSION 


62 


“IBMOT FO MOTA UMOID “ST —e jo Mor 


‘goIsn[o00 orureudp jo soSvys [eu Jo MoTA yeroyey 


‘roddn Jo MorA UMOID “4 “Y}00} OUTUROJSOg 


~ we STEED ae x 


aie 
I ‘zemoy Fo AOTA UMOID “ET 


‘(uinesnyy Apoqeeg sex ul wourrseds) 


‘ds snyjousojassppy “uorsnjo00 o1ureuAp jo sosejs [eu JO MOIA [eIoJeT “YJ “IOMOT 
JO MOIA UMOID ‘“q ‘oddn Jo MoIA UMOID “q “YI90} OUTUeOJSOg “AOU ‘ds mmosyasy 
uopouajvIS “UOISH[IIO o1uIeUAP Jo sosvjs [PUY JO MOIA [eIO}ET “DQ “IOMOT FO MITA UMOID 
‘q -roddn fo MoIA UMOID “YW “Y}99} OUTURDJSOg ‘suodsfysnsuD UopouajvIg “EI “DIY 


TWNYSALXS 


a YOIYSLNV 


CYNODONTS AND TRITYLODONTIDS 63 


new shearing surfaces and the loss of worn teeth in front, as well as numerous skull 
and skeletal features, suggest a close relationship between the tritylodontids and 
traversodontids. In addition there are several other similarities between the denti- 
tions of individual traversodontids and of Tritylodon. These are most marked in 
Scalenodon hirschsom and the new species of Massetognathus described above. In 
Tritylodon and S. hirschsom the rows of postcanine teeth are parallel to the longi- 
tudinal axis of the skull and are not arranged obliquely along the edge of the maxilla 
as in S. attridget, S. charigi and earlier cynodonts. The incisors and lower canines of 
S. hirschsom are procumbent and this, taken together with the parallel postcanine 
rows, may indicate that there was increased posterior jaw movement during mastica- 
tion. In Massetognathus the postcanine rows are not parallel but there is neverthe- 
less a marked tendency for the rows to be directed away from the edge of the face 
towards the midline of the skull (Romer, 1967). The nature of the shearing planes 
between the external surface of the lower postcanines and the internal surface of the 
external cusps of the upper postcanines was essentially the same in Tvitylodon and the 
two traversodontid genera (cf. Fig. 13C, F, I & L). In both Tvitylodon and the 
traversodontids lower postcanines occluded with two upper postcanines because of 
the extensive backward movement of the lower jaw during occlusion. The main 
difference lies in the presence of the additional cusps of the postcanines in Tvitylodon. 
However, cusps that were not present in the more primitive traversodontid S. 
angustifrons (Fig. 13A) were added to the crown of S. irschsoni (13D) and Masseto- 
gnathus (13G). 

In these latter animals cusps have been added to the uppers in front of the external 
and internal main cusps, i.e. in positions which suggest the initial steps in the forma- 
tion of the external and internal rows of cusps of the tritylodontid upper postcanines. 
It is significant that the largest cusps of tritylodontid upper postcanines are situated 
posteriorly and that the anterior cusps decrease progressively in size. The posterior 
accessory cusps on the external surface of the lower postcanines of traversodontids 
may also indicate the initial step in the greater development of the external row of 
cusps typical of tritylodontid lower postcanines. Although the postcanines of S. 
hurschsoni tended to resemble those of tritylodontids it is unlikely that the former 
reptile was ancestral to the latter; the power stroke was directed forwards in S. 
Jurschsoni, whereas it is the backwardly directed power stroke which appears to have 
characterized Tvitylodon occlusion. In Tritylodon the external and internal rows of 
cusps of the lower postcanines sheared between the external, central and internal 
cusps of the corresponding upper postcanines; therefore, if the ancestor of Tritylodon 
were to be found amongst the traversodontids, some indication of this occlusal 
pattern would be expected in one of the latter. In all the species of Scalenodon the 
transverse ridge of each lower tooth always occluded with the posterior surface of 
the transverse ridge of the preceding upper tooth; this shows that the lower jaw was 
not thrust far enough forwards before the power stroke for the transverse ridge of the 
lowers to be drawn backwards over the transverse ridge of the uppers. In the new 
species of Massetognathus however, the transverse ridges were drawn across one 
another during occlusion; this appears to be the only known traversodontid where 
this happened. Neither this species of Massetognathus nor S. hirschsoni appears to 


64 POSTCANINE OCCLUSION 


be directly ancestral to the tritylodontids, but, taken together, they show that some 
traversodontids were developing a postcanine dentition and mandibular movements 
which were very close to those of tritylodontids. Once two transverse ridges 
shearing past one another had been developed, it was a relatively simple matter to 
add more cusps in front of the uppers and behind the lowers, and thus to obtain 
postcanines of the tritylodontid type. In Fig. 13G & J an attempt has been made 
to homologise the cusps and regions of the crowns of the upper postcanines of the 
new species of Massetognathus and of Tritylodon. The posterior transverse row of 
cusps has been labelled A, B and C; the second row A!, B! and C! and the third row 
B” and C”. In Fig. 13H & K the same has been attempted for the lower teeth. It 
is clear that forms such as Exaeretodon, Gomphodontosuchus and S. charigi, which had 
lost the central cusp of the upper postcanines, could not have been ancestral to the 
tritylodontids; neither could forms such as S. attridgei with strongly developed 
anterior masticatory movements. 


VII. SUMMARY AND DISCUSSION 


The postcanine teeth of all the major groups of cynodonts have been briefly 
described and figured. 

Three new species of traversodontid cynodonts, Scalenodon hirschsoni, S. attridget 
and S. charigi have been named and briefly described from their postcanine teeth. 

An attempt has been made to trace the evolution of postcanine occlusion in 
advanced cynodonts. This is shown diagrammatically in Fig. 14. The term 
occlusion implies that there was tooth-to-tooth contact during the masticatory 
cycle; the teeth were constructed so that shearing, puncturing and crushing were 
possible between corresponding upper and lower teeth. Occlusal relationships 


Fic. 14. Origin of the postcanines of Tyvitylodon. For each species the superimposed 
crown views of upper and lower postcanines are shown next to a posterior view of an 
occluding pair. Heavy lines indicate the orientation of the shearing planes. White 
circles indicate the principal cusps of the upper postcanines and black circles the 
principal cusps of the lower postcanines. Arrows indicate the extent of backward 
movement, from the beginning of tooth contact to its tightly closed completion. 
A. Thrinaxodon sp. Tooth-to-tooth contact did not occur. B. Tvivachodon sp. 
C. Diademodon sp. Lowers occluded directly with uppers and small shearing surfaces 
were produced by wear. D. Scalenodon angustifrons. Crowns of uppers and lowers 
were modified to reduce destruction of the tips of the cusps, and transverse elongated 
shearing surfaces were present. These surfaces came into use as the lower jaw was drawn 
upwards and backwards. G. Ewaeretodon sp. A modification of the S. angustifrons 
pattern. H. Scalenodon hirschsoni sp. nov. Occlusion involved both an anteriorly 
directed power stroke and a backwardly directed one. E. Massetognathus sp. The 
transverse shearing surface of the lower postcanines was drawn across the transverse 
shearing surface of the corresponding uppers (this did not happen in D, G & H above); 
the transverse shearing surfaces were modified in that small longitudinal shearing 
surfaces were formed by wear. F. Tyvitylodonsp. ‘The addition of extra cusps, in front 
of the upper teeth and behind the lowers, increased the length of the longitudinal shearing 
surfaces (which were comparable to those formed by wear in Massetognathus). There 
were no transverse shearing surfaces. The series from Diademodon to Tritylodon shows 
a progressive increase in the extent of the backward movement of the lower jaw during 
the power stroke. 


— 


CYNODONTS AND TRITYLODONTIDS 65 


become progressively more complex within the cynodonts. 

In the early cynodonts, the Galesauridae and Procynosuchidae, the lower post- 
canines bit internal to the uppers, tooth-to-tooth contact between opposing post- 
canine teeth was not possible and matching shearing planes are therefore absent 
(Fig. 14A). In both these families replacement of the postcanine teeth was alternate. 

In the carnivorous cynodonts, the Cynognathidae and Chiniquodontidae, the 
lower postcanines still bit internal to the uppers, but matching shearing surfaces are 
occasionally found on the external surface of the lowers and internal surface of the 
uppers; this suggests that some form of shearing was possible, but the shearing 


AX THRINAXODON sp 


B TRIRACHODON sp Ay 


C DIADEMODON sp 


G EXAERETODON sp D SCALENODON ANGUSTIFRONS H scALeNopon HIRSCHSONI 


a 


66 POSTCANINE OCCLUSION 


mechanism was primitive in comparison with mammalian carnassials and presum- 
ably played only a minor role in mastication. Clear-cut alternate replacement of 
the postcanine teeth was lost. 

In the gomphodont cynodonts (Diademodontidae, Trirachodontidae and Traverso- 
dontidae) the lower postcanine teeth bit directly against the upper postcanines 
rather than internal to them. In the Trirachodontidae (Fig. 14B) the transverse 
ridges of the upper and lower postcanines alternated with one another but complex 
occlusal patterns were not developed. The crowns of the unworn postcanines of the 
Diademodontidae were characterized by one or two major cusps and an intricate 
pattern of smaller cusps and ridges; these were rapidly obliterated by wear so that 
small matching shearing planes were produced on the outer surface of the main cusp 
of the lower teeth and the inner surfaces of the main cusp of the uppers (Fig. 14C). 
However, the main cusp of the lower tooth, because it bit directly against the 
occlusal surface of the uppers (Fig. 14C), was rapidly worn down; the shearing 
surfaces can have been effective only for a short time. The continued possession of 
teeth with vertical shearing surfaces was nevertheless ensured by the addition of new 
gomphodont and sectorial teeth behind, worn teeth being lost from the front of the 
postcanine row. As would be expected, there was no alternate tooth replacement; 
occluding teeth were added sequentially at the end of the row during growth. 

The occlusal patterns characterizing the Diademodontidae and closely related 
forms were refined in the Traversodontidae, where high ridges and deep basins 
provided effective shearing surfaces. Because the tips of the cusps occluded either 
opposite basins or externally to matching teeth, they were not worn down as rapidly 
as in the Diademodontidae. In primitive traversodontids the postcanines did not 
erupt with accurately matching upper and lower shearing surfaces, but, unlike the 
teeth of Diademodontidae, they needed relatively little wear of the crown surface to 
produce them; in Scalenodon angustifrons these shearing surfaces were aligned both 
transversely and longitudinally (Fig. 14D). In order that both these planes could 
be used effectively during the power stroke of mastication, jaw movements during 
this phase must have been both upwards and backwards. The transverse ridge 
which connected the two main cusps of the lower postcanine sheared past the trans- 
verse ridge formed by the central and internal cusps of the upper postcanine. The 
backwardly directed power stroke ended when the transverse ridge of the lower 
postcanine abutted against the anterior surface of the transverse ridge of the follow- 
ing upper. The arrow in Fig. 14D indicates the extent of this backward movement 
of a lower postcanine relative to the matching upper postcanine teeth during the 
power stroke of occlusion. 

In a specimen belonging to a new species of Massetognathus (Fig. 14E) the basic 
Scalenodon type of postcanine was slightly modified. External cusps were added in 
front of the external main cusp of the upper postcanines and the longitudinal shearing 
plane was consequently increased in length. This was apparently coupled with an 
increase in the length of the backwardly directed component of the power stroke. 
The twomain cusps of the lowers commenced shearing in front of, rather than behind, 
the transverse ridge of the uppers. As the lower jaw was drawn backwards the 
lower cusps wore grooves between the internal and central cusps and between the 


CYNODONTS AND TRITYLODONTIDS 67 


central and external cusps of the uppers; these continued on to the anterior wall of 
the succeeding upper postcanine. Consequently in the new species of Masseto- 
gnathus what corresponded to the transverse shearing surface of Scalenodon angusti- 
frons was broken down into longitudinally orientated shearing surfaces on the sides 
of the main cusps. As in Diademodon, these grooves or shearing surfaces were 
produced by wearing away a substantial portion of the crown. 

In Tritylodon (Fig. 14F) these modifications observed in the postcanines of the new 
species of Massetognathus were taken a stage further. The length of the backwardly 
directed component of the power stroke was increased and cusps were added in front 
of the upper teeth and behind the lowers. These additional cusps were smaller than 
the main cusps and they formed two additional transverse rows. Longitudinally 
orientated shearing planes similar to those which resulted from wear in the new 
species of Massetognathus were present on freshly erupted hardly worn teeth in 
Tnitylodon. In Oligokyphus an additional row of cusps was added, increasing the 
length of longitudinally orientated shearing surfaces still further. The entire trend 
is towards a lengthening of the backward component of the power stroke. 

The large South American traversodontids, Exaeretodon (Fig. 14G), Proexaeretodon 
and Ischignathus, increased the length and height of the vertical shearing surfaces on 
the internal surfaces of the external main cusps of the upper teeth. The transverse 
shearing surfaces are obliquely orientated, the central cusp has been lost and a large 
external cusp added in front of the external main cusp of the uppers. For these 
reasons it is unlikely that these traversodontids could have been ancestral to the 
tritylodontids. 

In Scalenodon liyschsom (Fig. 14H) and S. attvidge: wear facets indicate that both 
longitudinally and transversely orientated shearing planes were present, but, unlike 
other traversodontids, they could make both forwardly and backwardly directed 
power strokes during mastication. 

The postcanine teeth of traversodontids and the tribosphenic molars of primitive 
mammals functioned in similar ways. Both have shearing surfaces on the vertical 
faces of the main cusps and both had jaw movements during the final stages of the 
masticatory cycle which were not directly orthal; in primitive therian mammals the 
power stroke had a marked transverse component (Crompton & Hiiemée 1969a & 0), 
while in traversodontids it had a strong posterior component. These movements in 
the horizontal plane permitted several shearing surfaces to be used as the jaws were 
closed. 

In traversodontids but not in the tritylodontids the mandibular symphysis was 
massive and presumably immobile during life. The left and right lower postcanine 
teeth were slightly further apart than the corresponding upper postcanines; the 
opposite is true of primitive mammals. These two characters of traversodontids 
suggest that during the final stages of mastication both mandibular rami were drawn 
directly backwards and occlusion had to occur on both sides simultaneously; the 
greater the extent of the backward movement the more nearly parallel the rows of 
postcanine teeth. This is not possible in a primitive mammal (Crompton & Hiiemae, 
1969a & 6). Significant transverse mandibular movements in cynodonts and 
tritylodontids were prevented by the massive transverse processes of the pterygoid 


68 POSTCANINE OCCLUSION 


bones and the structure of the postcanine teeth. The structure of the lower jaw of 
primitive mammals (Crompton 1963, Krebs 1969) suggests that remnants of the 
transverse processes of the pterygoids may have been present in some cases; it is 
possible that their reduction in early mammals was coupled with changes in jaw 
musculature permitting the introduction and strengthening of transverse mandibular 
movements. 

The mechanism involved in developing occlusion in gomphodont cynodonts and in 
mammals (Crompton & Jenkins, 1968) appear to have been similar. In the early 
forms of both groups the crowns of corresponding upper and lower teeth were shaped 
by wear to produce matching shearing planes; in both a complex series of cusps and 
ridges had to be obliterated by wear before the teeth could function efficiently. This 
is particularly true of the cynodont Diademodon, of the new species of Masseto- 
gnathus and of the mammal Eozostrodon (=Morganucodon). In the later travers- 
odontids, tritylodontids and mammals the postcanines and molars lacked superfluous 
crown structures that had to be worn down and the crowns already possessed 
shearing planes that were genetically determined rather than produced by wear. 
The numerous Middle Triassic cynodonts from South America and the abundant 
early mammal teeth should be studied in detail in order to clarify further this aspect 
of evolutionary change. 

The distribution of traversodontid cynodonts is briefly discussed; it suggests ready 
access between the continental masses of Africa and of South America during the 
Trias. The Traversodontidae may nevertheless have had a worldwide distribution. 


ACKNOWLEDGEMENTS 


I wish to thank Dr F. R. Parrington for the loan of the Tanzanian material in the 
University Museum of Zoology, Cambridge; Dr J. F. Bonaparte for presenting the 
Massetognathus jaw fragments described in this paper and for allowing me to study 
the magnificent collection of Triassic vertebrates at the Instituto Lillo in Tucuman, 
Argentina; Dr A. S. Romer for the opportunity to study the South American 
cynodonts in the collections of the Museum of Comparative Zoology, Harvard 
University; Dr A. J. Charig for his permission to study the cynodont material 
collected on the British Museum (Natural History)—University of London Joint 
Palaeontological Expedition to Northern Rhodesia & Tanganyika, 1963; and Drs 
A. J. Charig, K. Hiiemae, J. A. Hopson, J. Osborne and F. R. Parrington for reading 
the manuscript and for making many useful suggestions. The drawings were 
prepared by Mrs R. Rowen, the photographs taken by Mr A. Coleman and several 
drafts of the manuscript patiently typed by Miss M. Newton and Mrs I. Copeland. 

This work has been supported by grants from the United States National Institutes 
of Health (RO1-DE-02648) and the National Science Foundation (GB 4435). 


CYNODONTS AND TRITYLODONTIDS 69 


ABBREVIATIONS USED IN TEXT-FIGURES 


a.a.c.l. anterior accessory cusp of lower elle internal cusp of lower postcanine 
postcanine Gre internal cusp of upper postcanine 
a.a.c.u. anterior accessory cusp of upper p.a.c. posterior accessory cusp 
postcanine p.b. posterior basin 
af. anterior ridge p.c. posterior cingulum 
av. anterior valley ptr. posterior ridge 
a.w. anterior wall Pave posterior valley 
b.l. basin in lower postcanine p.w.f. postcanine wear facet 
b.u. basin in upper postcanine S. saddle 
CC. central cusp of upper postcanine Sh.s. shearing surface 
ie: embayment Unies transverse ridge 
e.cing. external cingulum tate transverse ridge of lower postcanine 
ec: external cusp of lower postcanine t.r.u. transverse ridge of upper postcanine 
Sci, external cusp of upper postcanine w.f. wear facet. 
en. enamel 
REFERENCES 


AnpbErsSON, J. M. 1968. The confused state of classification within the family Procynosuchidae. 
Palaeont. afy., Johannesburg, 11 : 77-84, 1 fig. 

ATTRIDGE, J., BALL, H. W., Cuaria, A. J., & Cox,C.B. 1964. The British Museum (N.H.) 
University of London Joint Palaeontological Expedition to Northern Rhodesia and Tangan- 
yika, 1963. Nature, London, 201 : 445-449. 

Bonaparte, J. F. 1962. Descripcion del craneo y mandibula de Evxaeretodon frenguellit, 

Cabrera y su comparacién con Diademodontidae, Tritylodontidae y los cinodontés 

sudamericanos. Pubines. Mus. munic. Cienc. nat. tvadic., Mar del Plata, 1 : 135-402, 

4 pls., 16 figs. 

1963. La Familia Traversodontidae. Acta geol. lilloana, Tucuman, 4 : 163-194, Io figs. 
1966. Una nueva “‘fauna’”’ tridsica de Argentina (Therapsida: Cynodontia Dicynodontia), 
Ameghiniana, Buenos Aires, 4 : 243-295, 2 pls., 29 figs. 

1967a. New vertebrate evidence for a southern transatlantic connexion during the 

Lower or Middle Triassic. Palaeontology, London, 10 : 554-563, 7 figs. 

——1967b. Dos nuevas “‘faunas”’ de veptiles Tvidsicos de Argentina. 1 Simposio internacional 
sobre estratigvafia y Palaeontologia del Gondwana. Resumenes de Trabajos presentados a 
las sesiones. p. 7-8. 

Brink, A. S. 1955. A study of the skeleton of Diademodon. Palaeont. afy., Johannesburg, 

3 : 3-39, I0 figs. 

1957. Speculations on some advanced mammalian characteristics in the higher mammal- 
like reptiles. Palaeont. afy., Johannesburg, 4 : 77-96, 5 figs. 

—— 1963a. Two cynodonts from the Ntawere Formation in the Luangwa valley of Northern 
Rhodesia. Palaeont. afy., Johannesburg, 8 : 77-96, 4 figs. 

—  1963b. Notes on new Diademodon specimens in the collection of the Bernard Price Insti- 
tute. Palaeont. afy., Johannesburg, 8 : 97-111, 7 figs. 

Bro, F., & ScHRODER, J. 1935. Beobachtungen an Wirbeltieren der Karrooformation. 
IX. Uber den Schadel von Gomphognathus Seeley. S.B. bayer. Akad. Wiss., 1 : 115-182, 
42 figs. 

BULLARD, E. 1969. The origin of the oceans. Scient. Am., New York, 221 : 66-75, 6 figs. 

Butter, P. M. 1961. Relationships between upper and lower molar patterns. Internat. 
Colloq. on the Evolution of Mammals. Kon. Vlaamse Acad. Wetensch. Lett. Sch. Kunsten 
Belgie, Brussels, pp. 117-126, 4 figs. 

Cuaric, A. J. 1967. Subclass Archosauria. Jn Harianp, W. B. e al. (Eds.) The Fossil 
Record. Geological Society of London, 708-718, 725-731. 

CoLpert, E. H. 1963. Relationships of the Triassic reptilian faunas of Brazil and South 
Africa, S. Afr. J. Sci., Cape Town, 59 : 248-253, 1 fig. 


70 POSTCANINE OCCLUSION 


Crompton, A. W. 1955. On some Triassic cynodonts from Tanganyika, Pyoc. zool. Soc. 
Lond., 125 : 617-669, 15 figs. 

1963a. On the lower jaw of Diarthrognathus and the origin of the mammalian lower jaw. 

Proc. zool. Soc. Lond., 140 : 697-750, pls. 1-2, 17 figs. 

1963b. Tooth replacement in the cynodont Thrinaxodon liorhinus Seeley. Ann. S. 
Afr. Mus., Cape Town, 46 : 479-521, 17 figs. 

1964. A preliminary description of a new mammal from the Upper Triassic of South 
Africa. Proc. zool. Soc. Lond., 142 : 441-452, 4 figs. 

Crompton, A. W. & ELLENBERGER, F. 1957. On a new cynodont from the Molteno Beds 
and the origin of the tritylodontids. Ann. S. Afr. Mus., Cape Town, 44 : 1-14, pl. 1, 
5 figs. 

Crompton, A. W. & HilEMAE, K. 1969a. Functional occlusion in tribosphenic molars. 

Nature, London, 222 : 678-679. 

1969b. Molar occlusion and mandibular movements during occlusion in the American 
opossum, Didelphis marsupials. J. Linn. Soc. (Zool.), London, 49 : 21-47, pl. 1, to figs. 

1969c. How mammalian teeth work. Discovery, New Haven, 5 : 23-34, 9 figs. 
Crompton, A. W. & JENKINS, F. A. Jr. 1967. American Jurassic symmetrodonts and 
Rhaetic ‘““Pantotheres’”’. Science, New York, 155 : 1006-1009, 3 figs. 

1968. Molar occlusion in late Triassic mammals. Biol. Rev., Cambridge, 43 : 427-458, 
pls. 3, 11 figs. 

Fourig, S. 1963. Tooth replacement in the gomphodont cynodont, Diademodon. S. Afr. 
J. Sci., Cape Town, 59 : 211-213, 1 fig. 

1964. Cynodonts of the Lystvosauvus and Cynognathus zones. D.Sc. thesis. Uni- 
versity of Stellenbosch. 

1968. The jaw articulation of Tvitylodontoides maximus. S. Afr. J. Sci., Cape Town, 
64 : 255-265, 4 figs. 

Haueuton, S. H. & Brink, A. S. 1954. A bibliographical list of Reptilia from the Karroo 
Beds of Africa. Palaeont. afy., Johannesburg, 2 : 1-187. 

Hopson, J. A. 1966. The origin of the mammalian middle ear., Am. Zoologist, Utica, N.Y., 

6 : 437-450, I1 figs. 

1969. The systematic position of the cynodont Sysphinctostoma snuthi and on a recon- 
sideration of postcanine succession in Diademodon (Reptilia, Therapsida). In press. 
Kemp, T. S. 1969. On the functional morphology of the gorgonopsid skull. Phil. Tvans. 

R. Soc., London, 256B : 1-83, 25 figs, pl. 1. 

KERMACK, K. A. 1965. The origin of mammals. Science Journal, London, 1 : 66-72, 5 figs. 
—— Lees, P. M. & Mussett, F. 1965. Aegialodon dawsom, a new trituberculosectorial 

tooth from the lower Wealden. Pyvoc. R. Soc. B, London, 162 : 535-554, 6 figs. 

Kitcuinc, J. W. 1968. On the Lystrosaurus zone and its fauna with special reference to 

some immature Lystrosauridae. Palaeont. afy., Johannesburg, 11 : 61-76, 5 figs. 
Kress, B. 1965. Ticinosuchus feyox nov. gen. nov. sp. Ein Pseudosuchier aus der Trias des 
Monte San Giorgio. Schweiz. palaeont. Abh., Basel, 81 : 1-140, pls. 3, 68 figs. 
1969. Nachweis eines rudimentaren Coronoids im Unterkiefer der Pantotheria (Mam- 
malia). Paldont. Z., Berlin, 43 : 57—63, pls. 4, 4 figs. 
Ktune, W. G. 1956. The Liassic thevapsid Oligokyphus. x xX 149, 12 pls. 66 figs. British 
Museum (Nat. Hist.), London. 

LeumMan, J. P. 1961. Cynodontia, pp. 140-191, 37 figs, in Tvaité de Paleontologie. Tome VI. 
Ppp. 1-1135. Masson et Cie., Paris. 

Menarp, H.W. 1969. The deep-ocean floor. Scient. Am. New York, 221 : 126-145, 11 figs. 

MENDREZ, C. H. 1967. Sur quelques critéres de distinction entre Thérocéphales et Cyno- 
dontes, pp. 429-437, 7 figs in Problémes actuels de Paléontologie (Evolution des Vertébrés) 
Editions du Centre National de la Recherche Scientifique, Paris, pp. 1-474. 

Mitts, J. R. E. 1964. The dentitions of Pevamus and Amphitherium. Proc. Linn. Soc. 
Lond., 175 : 117-133, pls. 2, 6 figs. 


CYNODONTS AND TRITYLODONTIDS 71 


Mitts, J. R. E. 1966. The functional occlusion of the teeth of Insectivora. J. Linn. Soc. 

(Zool.), London 47 : 1-25, pls. 

1967. A comparison of lateral jaw movements in some mammals from wear facets on 

the teeth. Avrchs. oval Biol. London 12 : 645-661, 14 figs. 

PaRRINGTON, F. R. 1936. On tooth replacement in theriodont reptiles. Phil. Tyans. R. Soc., 
London 226B : 121-142, 11 figs. 

— 1946. On the cranial anatomy of cynodonts. Proc. zool. Soc. Lond. 116 : 181-197, 

Io figs. 

1955. On the cranial anatomy of some gorgonopsids and the synapsid middle ear. 
Proc. zool. Soc. Lond. 125 : 1-40, 14 figs. 

Riegney, H. W. 1963. A specimen of Morganucodon from Yunnan. Nature, Lond. 
197 : 1122, 1 fig. 

Romer, A. S. 1967. The Chanares (Argentina) Triassic reptile fauna. III. Two new 
gomphodonts, Massetognathus pascuali and M. teruggii. Breviorva, Cambridge, Mass., 
264 : 1-25, 10 figs. 

SEELEY, H.G. 1895. Mesearches on the structure organization and classification of the fossil 
Reptilia. Part IX, section 3. On Diademodon. Phil. Tvans. R. Soc. B, London, 185 : 
1029-1041, pl. 89. 

Sit, W. D. 1969. The tetrapod-bearing continental Triassic sediments of South America. 
Am. J. Sci,, New Haven, 267 : 805-821, 3 figs, 

StockLEy, G. M. 1932. The geology of the Ruhuhu coal fields, Tanganyika Territory. 
Q. Jl geol. Soc. Lond., 88 : 610-622, pls. 1. 

Szatay, F. S. 1969. Mixodectidae, Microsyopidae and the Insectivore-Primate transition. 
Bull. Am. Mus. nat. Hist., New York, 140 : 195-330, pls 40, 28 figs 

Tatarinov, L. P. 1968. Morphology and systematics of the northern Dvina cynodonts 
(Reptilia, Therapsida; Upper Permian). Postilla, New Haven, 126 : 1-51, 8 figs. 

Watson, D. M. S. to11. The skull of Diademodon with notes on some of those of other 
cynodonts. Ann. Mag. nat. Hist., London, (8) 8 : 293-330, 9 figs. 

Youne, C.-C. 1959. Note on the first cynodont from the Sinokannemeyeria faunas in Shansi, 
China. Vertebr. palasiat., Peking, 3 : 124-131, 4 figs., 3 pls. 

—— 1961. On a new cynodont from N.W. Shansi. Verteby. palasiat., Peking, 5 : 109-114, 
pls. 1. 

ZiEGLER, A. C. 1969. A theoretical determination of tooth succession in the therapsid 
Diademodon. J. Palaeont., Tulsa, 43 : 771-778, 2 figs. 


A. W. Crompton, M.Sc., D.Sc., F.Z.S. 
Museum of Comparative Zoology 
HARVARD UNIVERSITY 

CAMBRIDGE 

Mass. 

S.A. 


PLATE 


Thrinaxodon liorhinus 


A. Oblique internal view of last three left lower postcanines. 
B. Oblique internal view of last five left upper postcanines. 


PEATE 1 


Bull. Br. Mus. nat. Hist. (Geol.) 21, 2 


A 


I——_ 0.5 cm——+ | 


PLATE 2 
A. Glochinodontoides gracilis (holotype, American Museum of- Natural History, no. 
2223). Crown view of first four left upper postcanines. 


B. Diademodon sp. (Bernard Price Institute, Johannesburg, no. 1675). Crown view of 
isolated postcanines; all except centre right are uppers. 


Bull. Br. Mus. nat. Hist. (Geol.) 21, 2 PEALE 2 


18.8) 


4 
’ 


— 


PLATE 3 


Cricodon metabolus (holotype, Cambridge University Museum of Zoology, Ruhuhu Field 
Catalogue no. 74). 
A. Crown view of 7th and 8th right lower postcanines. 


B. Crown view of 7th right upper postcanine. 


Bull. By. Mus. nat. Hist. (Geol.) 21, 2 PEALE 3 


I-00. 5cm~+>I 


- 


isc 


TEA NTDID A 


Scalenodon angustifrons (holotype, Cambridge University Museum of Zoology, Ruhuhu 
Field Catalogue no. 120B). 
A. Crown view of last two left lower postcanines. 


B. Crown view of last three right upper postcanines. 


Bull. By. Mus. nat. Hist. (Geol.) 21, 2 P 
LATE 4 


J ==(0)5) fil 


PLATE 5 


Scalenodon hirschsoni sp. nov. (holotype, B.M.(N.H.) no. R. 8577). 
A. Crown view of 5th and 6th right lower postcanines. 
B. Crown view of 5th right upper postcanine. 


Bull. Br. Mus. nat. Hist. (Geol.) 21, 2 PAGES 15 


Ii=0.5cm—+ I 


PLATE 6 
Scalenodon attridgei sp. nov. (holotype, B.M.(N.H.) no. R.8578). - 
A. Entire palate. 
B. Crown view of right upper postcanines. 


PLATE 6 


Bull. By. Mus. nat. Hist. (Geol.) 21, 2 


ek 
Ii=— 0.5 cm—+ I 


PLATE 7 


Massetognathus sp. (Yale Peabody Museum). 
Matching upper and lower postcanines. 
A. Crown views of 3rd, 4th and 5th left lower postcanines. 
B. Crown views of 3rd, 4th and 5th left upper postcanines. 


Bull. Br. Mus. nat. Hist. (Geol.) 21, 2 PEALE 7, 


i<— 0.5 cm—+ I 


4 


— > 


A LIST OF SUPPLEMENTS 
TO THE GEOLOGICAL. ‘SERIES - 
OF THE BULLETIN OF 


Pp. 213; 40. Plates; 2 Text figutes: ae pee ; 
. Et-Nacear, Z. R. Stratigraphy and Planktonic Poiuniniies “of 
Cretaceous—Lower Tertiary Succession in the Esna-Idfu Region, li 
Egypt, U.A.R. Pp. 201; 23 Plates; 18 Text-figures. 1066. (£10. ; 

. Davey, R. J., Downie, C., SARGEANT, W. A. S. & Wirttams, G. L 
Mesozoic and Cainozoic Dinoflagellate Cysts oe 248; 28 
figures,” 1960." £70.07 : 
. APPENDIX. Davey, R. J., DowniE, C., SaRbRane, W. A. s. &W. 
Appendix to Studies on Mesozoic and. Cainozoic Dinoflagellate C 
1969. 8op. - Ere 
. Etziott, G. F. Permian to Palaeocene Calas Algae Daay isy¢ 
Middle East. Be I11; 24 Plates; 1g Keaton os Re 12: 


Pp. 315; 31 Plates; 92 ievhgiea! ee a a ee 
. Cuitps, A. Upper Jurassic Rhynchonellid Brachiopods ae 
Salles re. = 12 Plates; 40 ee ge oe 5: es 


pPle ae nga a rete E Shi ae: 
slay); Printed in England by Staples Printers Limited at their Kettering, Northants, establishment 


rs 


THE LOWER MIOCENE RUMINANTS OF 
GEBEL ZELTEN, LIBYA 


BY 


WILLIAM ROGER HAMILTON | 


Pp. 73-150; 14 Plates, 13 Text-figures 


BULLETIN OF 
THE BRITISH MUSEUM (NATURAL HISTORY) 
GEOLOGY Vol. 21 No. 3 
LONDON: 1973 


THE BULLETIN OF THE BRITISH MUSEUM 
(NATURAL HISTORY), instituted im 1949, 15 
issued in five series corresponding to the Departments 
of the Museum, and an Historical serves. 

Parts will appear at irregular intervals as they become 
ready. Volumes will contain about three or four 
hundred pages, and will not necessarily be completed 
within one calendar year. 

In 1965 a separate supplementary series of longer 
papers was instituted, numbered serially for each 
Department. 

This paper is Vol. 21, No. 3 of the Geological 
(Palaeontological) series. The abbreviated titles of 
periodicals cited follow those of the World List of 
Scientific Periodicals. 


World List abbreviation 
Bull. Br. Mus. nat. Hist. (Geol.). 


© Trustees of the British Museum (Natural History), 1973 


TRUSTEES OF 
THE BRITISH MUSEUM (NATURAL HISTORY) 


Issued 14 June, 1973 Price £4.30 


THE LOWER MIOCENE RUMINANTS OF 
GEBEL ZELITEN, LIBYA 


By W. R. HAMILTON 


CONTENTS 
Page 
I. INTRODUCTION : : 6 P 4 : : : c 76 
II. SySTEMATIC DESCRIPTIONS : . é 6 : : é 79 
Tragulidae : : : : 0 : : : : 79 
Palaeomerycidae : : j ; : : : : 81 
Giraffidae 4 : : . ‘ j : : : 85 
Sivatheriidae . : : : : é : ; : 103 
Bovidae . : : : 2 . P 125 
Ill. THE EVOLUTION OF PRIMITIVE GIRAFFOIDS . : é 6 131 
IV. THE EFFECT OF THE OSSICONES ON GIRAFFOID EVOLUTION . : 134 
V. A CLASSIFICATION OF THE GIRAFFOIDEA . 3 é é 5 136 
VI. East AFRICAN RUMINANTS : : : F ‘ : i 139 
Tragulidae 5 : : : 5 c . : - 139 
Gelocidae ‘ b : : : : 3 : : 140 
Palaeomerycidae é 5 5 5 : ‘ 5 5 142 
Bovidae . : : : : : : : : : 145 
VII. REFERENCES . ; é : 3 : : : ; ; 148 
SYNOPSIS 


Ruminants from the Lower Miocene (Burdigalian) deposits of Gebel Zelten, Libya, are described. 
The skull and dentition of a new giraffoid—Zarafa zelteni— are described in detail. This genus 
exhibits dental characteristics which ally it to the palaeomerycids; however details of the 
cranial anatomy indicate a close relationship to the palaeotragines. Zarafa is classified as a 
palaeotragine and its palaeomerycid features are interpreted as evidence of a common ancestry 
for the two groups. The Palaeotraginae and Giraffinae are grouped in the Giraffidae. 

The skull and dentition of Prohbytherium magnieri indicate that it is a member of the 
Sivatheriidae and primitive features of the skull suggest the divergence of the two families 
soon after the origin of the Giraffoidea in the late Oligocene. 

The different evolutionary trends exhibited by the Giraffidae and the Sivatheriidae are 
related to the different fighting methods used in intra-specific combat. In the Giraffidae an 
elongation of the neck and limbs was possible while in the Sivatheriidae selective pressures 
existed tending to maintain the short neck and limbs. 


76 LOWER MIOCENE RUMINANTS 


The other Gebel Zelten ruminants are poorly represented but a new genus and species— 
Canthumeryx sivtensis—is described and identified asa palaeomerycid. A new tragulid species— 
Dorcatherium libiensis and three bovid species—Gazella sp., Protvagocerus sp. and Eotragus sp. 
are present in the fauna. 

A further study of the ruminants from the Miocene of East Africa, enables the species 
Palaeomeryx africanus and Walangania gracilis to be synonymized as Walangania africanus and 
the upper dentition of Propalaeoryx nyanzae is described. A new species—Gelocus whitworthi— 
is described, this is the first recorded occurrence of the Gelocidae in Africa. 

The influence of these new discoveries upon the accepted classification of the giraffoids is 
discussed. 


I. INTRODUCTION 


The fossil vertebrate fauna of Gebel Zelten, Libya was discovered by Arambourg 
(19g61a and b) who published preliminary notes on some new elements in the fauna. 
Further collections were made by R. J. G. Savage of Bristol University between 1964 
and 1968. Many crania of Prolibytherium magnierit were collected and as some of 
these were of superior quality to the holotype, described by Arambourg (1961a); 
a full and detailed study of this species has been made. The presence of a second 
giraffoid—Zarafa zelteni—was not known until 1968 when M. White of Bristol 
University, completed the preparation of a skull which had been discovered, enclosed 
in a sandstone block. These two species form the basis of this work but as the study 
proceeded its scope was expanded to include the other ruminants of the area and 
finally a revision of some elements of the East African Miocene fauna was made. 


Gebel Zelten 

Gebel Zelten lies about 200 km south of the Gulf of Sirte, Libya. It consists of an 
elongate mesa running northwest-southeast for about 140 km at 19° 30’—20° 30’E. 
28°-29°N. The ESSO Company oil camp of Zelten lies to the north of the gebel 
and the Oasis Oil Company of Libya camp lies to the south; the road between these 
camps crosses the gebel at its narrowest point where it is only 8 km. wide. In the 
west the gebel rises 40-60 m above the Zelten Rambla; it dips gently to the east and 
blends with the Calenscio Serir at its eastern end. The plateau is capped by marine 
sandstone which is Lower Miocene in age and the edges are dissected by steep walled 
wadis up to 3 km in length (Savage and White 1965). It is in these wadis that many 
of the vertebrate remains are found though some of the sites are on areas of washout 
from the wadis. 

Detailed geological studies of the area have been published by Magnier (1962) 
and Selley (1968 and 1969); a detailed study of the geology with reference to the 
vertebrate sites is in preparation (Savage pers. comm.). The vertebrate remains are 
found in fluviatile deposits which probably originated in a coastal, alluvial flood plain 
(Selley 1969). The conditions at the time of deposition are interpreted as those of 
the savannah by Desio (1935) and again by Savage and White (1965). 

Desio (1935) indicated that the Zelten deposits are Burdigalian and Helvetian in 
age and he stated that the deposits on the south side of Gebel Zelten are of Aquitanian 


GEBEL ZELTEN, LIBYA 77 


age. Arambourg and Magnier (1961) and Arambourg (1961a and b, 1963a and b.) 
have consistently placed the deposits in the Burdigalian, and Arambourg (1963b) 
states that the Gebel Zelten deposits rest on Oligocene marine beds and are overlain 
by Helvetian marine beds. Savage and White (1965) indicate a Burdigalian age and 
this was later refined (Savage in Selley 1969) to Early Burdigalian or Late Aquitanian. 


Terminology 

In most anatomical details the terminology used follows that of Sisson and 
Grossman (1953). The nomenclature applied to the dentition (Text fig. 1) 1s mainly 
after Arambourg (1947). In the upper molars the postero-lingual cusp, termed the 
hypocone by Arambourg (1947) is here termed the metaconule after Weber (1928). 
In the lower molars I have treated the antero-lingual corner as if the paraconid has 
been entirely lost, thus the antero-lingual cuspid is the metaconid with an anterior 
mesostylid. The ‘Palaeomeryx fold’ is used to define any fold of enamel which runs 
vertically down the postero-labial face of the protoconid into the median valley. 


a b ¢c d 


Fic. 1. Ruminant molar and premolar cusp nomenclature. (A) Third upper premolar. 
(B) First upper molar. (c) Second, third and fourth lower premolars. (Dp) Second and 
third lower molars. Upper dentition. a: parastyle. b: paracone. c: metacone. d: 
metastyle. e: mesostyle. f: protocone. g: accessory crest. h: metaconule. i: ento- 
style. Lowery dentition. j: mesostylid. k: metaconid. 1: metastylid. m: entoconid. 
n: entostylid. o: hypoconid. p: ectostylid. q: protoconid. r: parastylid. s: para- 
conid. +t: hypoconulid. u: entoconulid. v: anterior fossette. w: posterior fossette. 


78 LOWER MIOCENE RUMINANTS 


The abbreviations used in reference to the dentition follow the convention in 
general use in Britain and America. I, C, P and M represent incisor, canine, pre- 
molar and molar respectively; the tooth is then defined by a number added above or 
below the line to indicate presence in the upper or lower jaw; thus Pz, is the lower, 
fourth premolar which is in contact with My, the first lower molar. The deciduous 
cheek teeth are referred to as D1, D; etc. The external side of the tooth is labial and 
the internal side is lingual. Anterior and posterior with reference to the dentition, 
indicate those directions which apply if the mandible or maxilla is in the horizontal 
position. 


Frontal Appendages 

In current usage the term ‘horn’ can refer to any cranial appendage but in this 
work a restriction of the term is applied. In the ruminants the type of frontal 
appendage is some times the main criterion on which the classification of a genus is 
based as stated by Pilgrim (1941) : 

‘“, . . the varying types of frontal appendage—horns—constitute one of the most 
important distinctions between the different families of the Pecora.’ 
In this situation it is clearly desirable that separate terms be applied to the different 
types of frontal appendage. Voorhies (1969) listed four types of frontal appendages 
in the living artiodactyls as: 
‘I. the unshed true horns growing on the bony core in the Bovidae, 2. the 
deciduous antlers of the Cervidae, 3. the annually-shed horny sheath growing 
over a permanent, vascular bony core in the Antilocaprinae, and 4. the bony 
core permanently covered by skin (‘velvet’) in the Giraffidae.’ 

The first three of these appendages are referred to as; ‘horns’, ‘antlers’ and ‘horn- 
cores’ respectively but no widely accepted term exists for the giraffid appendage. 
Lankester (1907) used the term ‘ossicone’ to refer to this appendage and defined 
ossicones as: 

“. . . independently ossifying bony cores which are found in Okapia and 
Giraffa on the frontal and parietal areas and in the giraffe also in the median 
position.’ 
A slight widening of the application of this term was made by Ginsburg and Heintz 
(1966) who applied the term to the palaeomerycid appendage and its application to all 
giraffoid cranial appendages is desirable. 


Abbreviations 

The prefix ‘M’ refers to specimens in the collections of the British Museum of 
Natural History, London: ‘B.U.’ in the Department of Geology, University of 
Bristol and ‘P’ in the Institut de Paléontologie, Paris. Specimens described in 
chapter 4 are the property of the National Museum, Nairobi, Kenya and are defined 
by the prefix ‘K’. 


Classification 

The system of classification used in this work differs slightly from that of Simpson 
(1945), this is mainly due to alterations within the Giraffoidea and primitive 
Cervoidea. The Palaeomerycidae is treated as a family of the Giraffoidea and follow- 


GEBEL ZELTEN, LIBYA 79 


ing the suggestion of Ginsburg and Heintz (1966), those genera of the family 
Palaeomerycidae which lack frontal appendages, are removed to the separate family 
Dremotheriidae. The family Blastomerycidae is grouped with the Dremotheriidae 
in the Dremotherioidea. The position of the Dromomerycidae is uncertain and 
requires further study, but in this work the family is treated as a group probably 
originating in the nearctic region and having no direct relationship to the Palaeo- 
merycidae. 

The family Giraffidae has been split by the establishment of the Sivatheriidae as a 
separate family. 


ACKNOWLEDGEMENTS 


I would like to express my deepest thanks to all those who have helped in making 
this work possible. Dr. R. J. G. Savage suggested the topic and by his encourage- 
ment, advice and friendship, he has contributed much towards its completion. The 
technical staff of the Department of Geology, University of Bristol, have all helped 
and I would particularly like to thank Mr. M. White for his work in preparation of the 
material and Mr. R. Godwin who prepared the plates. 

I would like to thank the staffs of the museums that I have visited. Professor 
M. Crusafont Pairo of Sabadelle, Spain and Professor Lehman of |’Institut de 
Paléontologie, Paris; have allowed me access to the collections and provided facilities 
forstudy. Dr. A. Sutcliffe of the British Museum of Natural History, allowed me to 
use the collections and facilities and the Keepers of palaeontology and zoology 
extended facilities on which I borrowed material. 

Dr. L. S. B. Leakey allowed me to study and redescribe the ruminant material from 
Kenya and Dr. A. W. Gentry gave advice and comment on the intricacies of bovid 
classification. Dr. Churcher provided up to date information on his study of the 
East African giraffids which helped to avoid any overlap in our studies. 

This study was carried out under a N.E.R.C. Research Studentship and the Univer- 
sity of Bristol provided me with facilities during the tenure of this studentship from 
1967 to 1970. 


Il. SYSTEMATIC DESCRIPTIONS 
Family TRAGULIDAE Milne-Edwards 1864 


DiaGnosis: Small primitive ruminants; lacking frontal appendages. Dentition 
primitive but with upper incisors reduced or absent. Upper canines large, especially 
inthe male. Molars bunodont but showing selenodonty in advanced forms. Limbs 
showing features of advanced ruminants but with varying degrees of fusion exhibited 
by the metacarpals and metatarsals. Navicular and cuboid fused. (After Milne- 
Edwards 1864). 


Genus DORCATHERIUM Kaup 1833 


Diacnosis: This genus was defined by Whitworth (1958 p. 3) whose diagnosis is 
followed here. 


TYPE SPECIES: Dorcatherium naw Kaup 1833. 


80 LOWER MIOCENE RUMINANTS 


Dorcatherium libiensis sp. nov. 


Diacnosis: A small species of Dorcatherium. Length of lower tooth row P3—M3 
about 39 mm. 


REMARKS: This species is established on a size basis and further work in the Gebel 
Zelten area may reveal wide variation in the species; however as the species is very 
rare at Gebel Zelten and as collecting in the area has been terminated it was decided, 
with some hesitancy, to establish the species on the basis of a single specimen. 


HoLotypPe: M.26684. A fragmentary right mandible with Ps to Me and the 
alveoli of P; and P2 preserved. 


Locatity: The Lower Miocene (Burdigalian) deposits of Gebel Zelten, Libya. 


Lower Dentition. The molars are heavily worn but the main details of their 
anatomy are visible (pl. 1, fig. 1). Mi is complete though badly cracked posterior 
to the median valley and the postero-lingual corner of Mz is missing. The molars 
are bunodont as in D. chappuist and D. nawi and strong anterior and posterior 
cingula were present on M; and Mz. The posterior face of the protoconid bears a 
strong fold similar to a ‘Palaeomeryx fold’ but more lingually situated and similar to 
that of D. chappuist. The postero-lingual region of the metaconid carries a deep 
vertical groove on both molars, as in D. naw and D. chappuisi this fold seems to be 
characteristic of the genus Dorcatherium. A small ectostylid is present in the median 
valley as in D. naut, this stylid is usually absent in D. chappuisz. 

The anterior end of P3 is missing but P4is complete. The premolars are elongate 
and similar to those of D. chappuisi and D. naw. The dentition of D. libiensis is 
thus similar to that of D. chappuwisi and is distinguished from this species and D. 
pigottt on a size basis only. 

The presence of this mandible in the Gebel Zelten fauna serves to establish the 
presence of the genus in North Africa at this time but gives no indication of the 
relative abundance of tragulids at Gebel Zelten, as specimens of this size and smaller, 
are relatively rare in the collection (Savage and White 1965). 


TABLE I 
D. hbiensis D. chappuisi D. pigott 
M.26684 (Whitworth) (Whitworth) 
Length Width Length Width Length Width 
P3 10:0 mm 36mm 13:55mm 5‘I mm 8-4 mm 3:1 mm 
Pa 96mm 40mm 12:3 mm 6-0 mm 7-9 mm 3°38 mm 
Mi 9-3 mm 58mm 11:7mm 7:2 mm 8-2 mm 4°38 mm 
Moe IIl-o mm 66mm 12:9 mm 9:0 mm 8-9 mm 5°3 mm 


Superfamily GIRAFFOIDEA Simpson 1931 


DiaGnosis: Medium to large sized ruminants. Cheek teeth brachyodont or 
occasionally hypso-brachyodont. Enamel of cheek teeth usually rugose. Ossicones 
present in male and sometimes female. Metapodials fully fused. 


GEBEL ZELTEN, LIBYA 81 


ComMENTS: Thisis a well defined group of ruminants which is probably related more 
closely to the Cervoidea than the Bovoidea and is in many respects more primitive 
than either group. 


Family PALAEOMERYCIDAE Lydekker 1883 


Diacnosis: A group of primitive giraffoids exhibiting features that may indicate 
a close relationship to the cervoids. Ossicones are present and in some species these 
have a long proximal region and a whorl of short tines distally. The mandible is 
shallow with brachyodont selenodont molars which have lightly rugose enamel. P 
may be present. Metastylid and entostylid usually very prominent and strong 
cingula are present anteriorly and posteriorly. A ‘Palaeomeryx fold’ is often present. 
Labial ribs of the upper molars prominent. Accessory crests often present in the 
fossettes and entostyle usually present in the median valley. 


Genus CANTHUMERYYX nov. 


Diacnosis: A medium sized ruminant, about as large as the fallow deer, Dama 
dama. Lower dentition similar to Propalaeoryx but lacking Py. Lower molars 
relatively high with weaker mesostylid and a stronger more flexed metastylid than is 
usual in the palaeomerycids. Strong anterior and weak posterior cingula on M, and 
Mz. Premolars elongate similar to usual palaeomerycid pattern but strong entostylid 
on P4. 

TYPE SPECIES: Canthumeryx sirtensis sp. nov. 

Diacnosis: As for genus. 


DERIVATION OF NAME: The generic name is from Canthus a character of Greek 
mythology: according to Appollonius: 
‘Fate had decreed that he and the great seer Mopsus should wander to the ends of 
Libya to be destroyed.’ (Rieu 19509). 
The trivial name refers to the Sirte basin in which the specimens were discovered. 
Hototyre: A mandibular fragment with D3 to Ms, the last molar being only 
partially erupted. Ms, P4 and Pe have been dissected out. 
Locatity: The Lower Miocene (Burdigalian) of Gebel Zelten, Libya. 
MATERIAL: 
M.26682 Holotype. 
M.26683 A right mandibular fragment with D4 and M; erupted. P3 and P4 
dissected out. 
B.U.zo111 An isolated lower right M3 showing moderate wear. 
Lower Dentition. The lower dentition forms a closed series from P2 to M3 and P; 


is absent as in Palaeomeryx but in contrast to Propalaeoryx. The enamel of the 
molars is finely rugose and the molars are higher and more elongate than in Palaeo- 


82 LOWER MIOCENE RUMINANTS 


meryx but lower and slightly wider than in Propalaeoryx. The metaconid of My, is 
transversely flattened with a weak mesostylid, a strong lingual mb and a strong 
metastylid which is flexed more lingually than in Palaeomeryx and is longer and more 
slender than in Propalaeoryx. The entoconid has a strong lingual rib, the cuspid is 
almost parallel to the axis of the molar as in Propalaeoryx whereas in Palaeomeryx 
it has a more diagonal orientation. The posterior end of the entoconid is 
reduced and rounded in Mj, (pl. 1, fig. 2). The hypoconid is isolated until 
very late in wear and the anterior fossette would be entirely worn away before 
the hypoconid wear trace joined that of the protoconid. The hypoconid is much 
lower than the protoconid, but due to the increased overall height of the tooth, this 
difference is less marked than in Palaeomeryx. The posterior end of the hypoconid 
is produced lingually forming the posterior end of the tooth and causing the posterior 
fossette to open lingually in M, (pl. 1, fig. 3). 

Mg is very similar to My but the posterior end of the entoconid bears a strong keel, 
causing it to extend further posteriorly and tending to close the posterior fossette 
which opens at the postero-lingual corner of the tooth; this contrasts with Pro- 
palaeoryx in which the entoconid of Me is rounded posteriorly and the posterior 
fossette opens lingually asin My. In Palaeomeryx the posterior end of the entoconid 
usually bears a strong crest in M; and M2. 

Mz has a feeble mesostylid and a strong metastylid. The entoconid is transversely 
flattened and its anterior region consists of a strong crest of enamel which meets the 
anterior face of the protoconid. The posterior region of the entoconid consists of a 
strong crest and from its posterior end the long mentoconulid curves posterolabially, 
to blend into the middle of the lingual face of the hypoconulid. The protoconid 
joins the posterior end of the metaconid closing the fossette even in the unerupted 
condition ; this region is very variable in Palaeomeryx but in Propalaeoryx it is similar 
to Canthumeryx. The posterior end of the hypoconid is short, it meets the 
hypoconulid but fails to reach the entoconulid. The crescentic hypoconulid is lower 
than the hypoconid. The molars each have a strong ectostylid in the median 
valley (pl. 1, fig. 4) and Mg has a small stylid in the posterior valley. A strong 
anterior cingulum is present on each molar and feeble posterior cingula are present 
on M, and Mo. 

The Pg of Canthumeryx is generally similar to that of Palaeomeryx or Propalaeoryx. 
The metaconid is the highest part of the tooth, it is strongly swollen anteriorly (pl. 1, 
fig. 5) and produces a strong wing posteriorly, these features are similar in Palaeomeryx 
but in Propalaeoryx the anterior and posterior projections are absent. The pro- 
toconid is joined to the metaconid by a strong ridge of enamel as in Palaeomeryx. 
The entostylid is very strong in Canthumeryx (pl. I, fig. 5), curving across the whole 
posterior face of the tooth as in Propalaeoryx and in contrast to Palaeomeryx in which 
it is reduced lingually. The entoconid of Palaeomeryx usually curves postero- 
lingually at its lingual end but there is no indication of such a curvature in Canthu- 
meryx or Propalaeoryx. The paraconid and parastylid are very strong and widely 
divided in Canthumeryx (pl. 1, fig. 5) and Propalaeoryx whereas in Palaeomeryx they 
are usually weaker and less widely divided. The labial face of the P, is swollen 
labially in Palaecomeryx but in Canthumeryx and Propalaeoryx this swelling is absent 


GEBEL ZELTEN, LIBYA 83 


and the wall is vertical. A strong groove on the labial wall separates the hypoconid 
from the protoconid, this groove is very strong in Palaeomeryx weaker in Canthumeryx 
and weaker again in Propalaeoryx. 

Ps is more elongate than Py; the metaconid is lower than in Py and it has no 
posterior fold or anterior swelling, it is also situated further posteriorly than on the 
Py (pl. 1, fig. 5). The posterior region consists of a hypoconid and an entoconid as in 
the P, but the entostylid is joined to the posterior face of the entoconid from which 
it curves postero-lingually and does not join the hypoconid (pl. 1, fig. 5); this is 
probably an individual variation which is also found in Palaeomeryx and Walangania 
and in these genera it is more usual for the posterior region of the P3 to resemble that 
of the P,. 

The Pz of Canthumeryx is relatively simple with a single, conical, primary cuspid 
in the central region from which an unforked anterior crest is produced; this curves 
lingually at its anterior end. A posterior swelling and a postero-lingual crest are 
produced from the primary cuspid. The posterior region is much lower than the 
primary cuspid, it consists of a single transverse crest which falls away posteriorly. 
Strong anterior and posterior cingula are present on all the premolars. 

The Dy, is heavily worn in both specimens. It is elongate and trilobed; its 
anterior end is narrower than the posterior end and the anterior, median and 
posterior fossettes are joined (pl. 1, fig. 2). The anterior fossette is bounded by a 
strong labial cuspid and a narrow lingual cuspid, the anterior end is closed by a small 
stylid. In both specimens the anterior region is very heavily worn and very little 
surface detail is visible. The metaconid is high and selenodont as in the molars 
(pl. 1, fig. 2), it has a strong metastylid which communicates with the high entoconid. 

The posterior region of the entoconid is shortened as in the Mj and the posterior 
fossette opens lingually (pl. 1, fig. 2). The protoconid is stout and crescentic, in the 
heavily worn condition its wear trace is joined to the antero-labial cuspid. The 
hypoconid is higher than the protoconid but this may be a wear factor. The Dghasa 
very strong ectostylid in the median valley. The posterior cingulum is strong and the 
anterior cingulum continues along the labial face as far as the anterior valley, in 
which there is a weak cingulum. 

The D3 is elongate narrowing anteriorly. The primary cuspid lies in the middle 
of the tooth and has a feeble lingual cuspid. The anterior region is similar to that 
of Ps with a long crest giving rise to antero-lingual and lingual branches. The 
posterior region has a single central hypoconid which is joined by a crest to the primary 
cuspid. The hypoconid produces a posterior branch which curves lingually at its 
posterior end and a lingual branch which curves posteriorly, a large enamel island is 
produced between these branches. 

The Dg is known from the alveoli only (pl. 1, fig. 4); these are single, anterior and 
posterior and indicate that D2 was slightly less elongate than the Ds. The absence 
of a D, indicates that P; was also absent. 

The dentition of Canthumeryx resembles that of Propalaeoryx more closely than 
any other ruminant, and both resemble Palaeomeryx. Differences of the metastylid, 
entoconid, height and width serve to distinguish the molars of Canthumeryx from 
those of Palaeomeryx and Propalaeoryx and many details of the fourth premolars 


84 LOWER MIOCENE RUMINANTS 


present differences between these genera. The absence of a Pj in Canthumeryx is an 
important difference distinguishing it from Propalaeoryx. 


TABLE 2 
The Lower Dentition of Canthumeryx 
M.26682 M.26683 B.U.20111 
Length Width Length Width Length Width 
D3 16-3 mm 5°7 mm -— — — — 
D4 22:2 mm — 230mm =I1'I mm — — 
P2 13-6 mm 5°3 mm = — — — 
P3 — — 18-7 mm 8-6 mm — — 
P4 15-8 mm 75mm 19-0 mm 9:8 mm — = 
Mi 195mm I10mm 201mm 14:0mm —_— — 
Me 203mm 13°6mm — — — — 
M3 292mm 13:3 mm -— — 312mm  13'7mm 


Palaeomeryx sp. 


The presence of a species of the genus Palaeomeryx in the Gebel Zelten fauna is 
indicated by two fragmentary molars; M.26691 and B.U.20112. The specimens are 
both third molars of which the former is the more complete. 

The metaconid is broken off but its postero-labial region indicates that it was 
joined to the protoconid and entoconid. The entoconid is transversely compressed 
and its posterior region is shortened, thus the posterior fossette opens lingually in 
contrast to Canthumeryx. The protoconidis crescentic and very stout, a “‘Palaeomeryx 
fold’ may have been present but the posterior face of the protoconid is very heavily 
worn. The anterior end of the hypoconid is produced anteriorly and its posterior 
end which joins the entostylid is much longer than in Canthumeryx. The hypo- 
conulid is stout and curves around the posterior end of the tooth, joining the entostylid 
and enclosing a posterior enamel island in contrast to Canthumeryx in which the 
posterior enamel island would not be formed in this position. A strong ectostylid 
is present in the median valley and a feeble stylid is present in the posterior valley of 
BaUi2onr2: 

These specimens are distinguished from Canthumeryx by details of their dental 
anatomy and also by their smaller size; they resemble Prolibytherium closely in size 
but are more brachyodont and differ in anatomical details from this genus. 


_ TABLE 3 


The Lower Molars of Palaeomeryx sp 
M.26691 B.U.2z0112 K.R.442.51 


Mg 

Length 24°2 mm — 28-I mm 
Width of anterior lobe I1-5 mm — 12°5 mm 
Width of posterior lobe I1-o mm II-o mm 1370 mm 


Width of accessory lobe 6-6 mm 6-7 mm 6-7 mm 


GEBEL ZELTEN, LIBYA 85 


Palaeomerycidae Indet. 


A single pair of ossicones M.266g90 (pl. 1, fig. 6), cannot be definitely assigned to any 
group of the Giraffoidea. These ossicones diverge at an angle of 40° and slope 
posteriorly at an angle of about 50° from the vertical. The bone surface has many 
fine vertical striations which fade out well above the base and it is unlikely that a 
horny sheath could have been present. The ossicones were very centrally positioned 
on the cranium and the region between them curves smoothly with no sign of a 
median suture. The small area of cranium that is preserved, indicates that the 
animal was slightly larger than Prolibytherium. 

The cervid genus Dicrocerus has long pedicles which are comparable in form with 
this specimen but in Dicrocerus the pedicles were supra-orbitally situated and were 
less divergent. The ossicones of Climacoceras diverged at an angle of about 60° 
(MacInnes 1936), their internal structure is similar to ordinary bone with a core of 
vesicular structure; this agrees with M.26690. MaclInnes (1936) also states that the 
shaft of Climacoceras was nearly straight throughout its length. The ossicones of 
Climacoceras may represent a condition derived from ossicones similar to M.26690. 


Family GIRAFFIDAE Gray 1821 


Diacnosis: Giraffoids in which the neck and limbs are usually lengthened. 
Ossicones small, consisting of a single tine. Degree of facial flexion small. Cheek 
teeth brachyodont; upper molars with strong mesostyle. Paracone and metacone 
having a diagonal orientation on the molar. - Lower premolars exhibiting molariza- 
tion. On the fourth lower premolar, the metaconid is strong and the hypoconid and 
entoconid are separated from the protoconid. ‘Palaeomeryx fold’ usually absent. 


ComMENTs: This group previously included the Sivatheriidae which is here 
treated as a separate family of the Giraffoidea. 


Subfamily PALAEOTRAGINAE Pilgrim rort 


D1aGnosis: Primitive, medium sized giraffids, usually with one pair of supra- 
orbital, frontal ossicones. A second pair of ossicones may be present on the anterior 
extremities of the frontals. Skull usually elongate. Cheek teeth brachyodont. 
Limbs and neck slightly elongate. (After Colbert 1935a.) 


Genus ZARAFA nov. 


Dracnosis: A very primitive palaeotragine with flattened, laterally expanded 
frontals and frontal sinuses in the supraorbital region. Supraorbital ossicones 
present. Paired lacrymal foramina present on the anterior edge of the orbit. 
Basicranial and basipalatal planes almost parallel. Maxilla very shallow. Cheek 
teeth primitive and very brachyodont. A strong accessory crest present on the 
posterior region of the metaconule. 


86 LOWER MIOCENE RUMINANTS 


Zarafa zelteni sp. nov. 


DiaGnosis: As for genus. 


DERIVATION OF NAME: The generic name is from the Arabic for ‘giraffe’. The 
trivial name is from Gebel Zelten, the area from which the type specimen was 
collected. 


Ho.otyre: An almost complete but edentulous skull (M.26670). The premaxilla 
and anterior region of the maxilla are missing and only the proximal region of the 
nasals is preserved. The lingual wall of the third molar is the only dental fragment 
preserved. 


LocaLity: The material is all collected from the Lower Miocene (Burdigalian) 
deposits of Gebel Zelten, Libya. 


MATERIAL: 
M.26670 Holotype. An almost complete skull of an adult individual. 
M.26671 A right maxillary fragment with P4 to M%. The dentition exhibits 
medium wear. 
M.26672 A left maxillary fragment with D2 to D4. The first two permanent 
molars are dissected out. 
M.26673 A cranial fragment consisting of the supra-occipital and parietal 
region. 
M.26674 A cranial fragment with the frontal-parietal suture and the anterior 
part of the frontals preserved. 
M.26675 A fragment of right mandible with Mg showing light wear. The 
ascending ramus and condyle are preserved, though badly shattered. 
M.26676 A heavily worn M3. 
M.26677_ A lightly worn Mg. 


Skull. The skull was found enclosed in a large sandstone nodule from which it was 
removed by the standard acetic acid preparation method. The postorbital region 
is in an excellent state of preservation but much of the preorbital region is missing. 
Slight crushing has occurred in the preorbital region. The specimen is from a mature 
individual but the acid preparation has opened and defined the sutures; these are not 
visible in areas prepared by hand. 

Maxilla. It is likely that the maxilla was very shallow and probably resembled 
that of the juvenile giraffe. The postero-lateral region of the maxilla is missing but 
its shape is indicated as an internal cast (pl. 2). The facial tuberosity lies above M2. 
The palatine process of the maxilla is badly broken and interpretation of the surface 
features is difficult. The surface is shallowly convex, its posterior edge extends to the 
maxillary tuberosity and into the orbit where it contributes to the lacrymal bulla. 
The anterior palatine foramen lies on the palatine-maxillary suture opposite 
theanterior end ofthe M2; more posteriorly than in Okapiabut similarto Givaffa. The 
anterior part of the bone is missing from the level of the anterior edge of P?. 
The maxilla extends behind the third molar, forming a large maxillary tuberosity 
which is badly broken in the specimen. 

Nasal. A small part of the nasal is preserved on the antero-dorsal edge of the 


GEBEL ZELTEN, LIBYA 87 


prelacrymal vacuity. The bone is very flattened in the same plane as the frontal, as 
in Palaeotragus microdon. 

Lacrymal. The large lacrymal forms the posterior edge of the prelacrymal 
vacuity and extends into the orbit. The antero-lateral face of the bone is concave 
in contrast to Okapia in which it is plane or Givaffa in which it is convex. The 
concavityin Zarafa results from the lateral expansion of the frontal bones. Thelacry- 
mal is expanded dorsally between the orbit and the prelacrymal vacuity. This 
dorsal expansion is more marked than in the other giraffids and may be due to the 
expansion of the frontals but a large lacrymal is also found in Dremotherium. A 
small lacrymal tubercle stands on the antero-dorsal edge of the orbit as in Okapia 
and paired lacrymal foramina are present behind the edge of the orbit. The 
maxillary foramen lies posterior to the lacrymal tubercle in the same position as in 
Okapia. The lacrymal bulla is badly broken posteriorly. 

Jugal. The jugal forms the ventral and postero-ventral edges of the orbit and 
contributes about half of the postorbital bar; as in Okapia a strong ridge forms the 
ventral edge of the orbit. The lateral face of the jugal is concave and the ventro- 
lateral region of the bone is badly eroded. The facial region is large and elongate 
resembling the cervids rather than Okapza. 

Palatine. Two parallel depressions run antero-posteriorly along the palatine. 
The bone is badly eroded posteriorly but it is preserved as a vertical plate in the 
pterygo-palatine fossa which is shallower but otherwise similar to that of Okapia. 

Frontal. The orbital region of the frontal is concave with the orbital opening 
of the supraorbital canal lying in the most dorsal part. The ethmoid foramen lies 
ventro-medial to the supraorbital canal. The frontal-parietal suture runs dorsally 
from the alisphenoid to the top of the skull and medially across the dorsal face to the 
median suture (pl. 3). The temporal region of the frontal is very small its concave 
ventro-lateral face resulting from the great expansion of the posterior supraorbital 
crest. A strong postorbital ridge runs transversely between the supraorbital process 
of the frontal and the squamosal bone. The frontal forms the dorsal edge of the 
preorbital vacuity and dorso-lateral to this the bone thickens forming a high 
supraorbital crest. As in Okapia the supraorbital foramen is directly above the 
orbital opening of the supraorbital canal; a shallow concavity lies anterior to the fora- 
men but there is no supraorbital groove in Zarafa. Lateral to the foramen the 
bone rises sharply to a peak and a process has been broken off revealing an extensive 
supraorbital frontal sinus which indicates the presence of a supraorbital ossicone. 
Ossicones are found in a similar position in Palaeotragus microdon and Samotherium 
sinense (Bohlin 1926) and this is probably the primitive position of ossicones in the 
Giraffidae. Postero-medial to this region is a strong lateral ridge which continues on 
the parietal. 

Parietal. The temporal face of the parietal is dorso-laterally inclined with a 
convex anterior region and a concave posterior region. The parietal crest crosses 
the dorsal part of the temporal region and probably continued as far as the edge of 
the nuchal crest but the posterior region is missing. The dorsal face of the parietal is 
shallowly concave with raised lateral and medial ridges. 

Occipital. The mastoid foramen lies on the postero-lateral face of the supra- 


88 LOWER MIOCENE RUMINANTS 


occipital region and the occipital forms its ventro-medial wall (pl. 4, fig. 1). The 
shape of the nuchal crest was probably similar to that of Okapia but the supra- 
occipital region is broken dorsally (pl. 4, fig. 1) and most of the nuchal crest is 
missing. The occipital condyles and foramen magnum are large in Zavafa and 
dorso-medial to the edge of the condyle the bone surface is concave but it is produced 
as a large swelling over the foramen magnum, a similar swelling is present in 
Palaeotragus microdon but is less pronounced in Okapia and absent in Givaffa and 
Prolibytherium. Dorsal to the swelling the bone is excavated as insertion for the 
semispinalis capitis muscle; these excavations are shallower than in Okapia. A 
weak median occipital crest stands between the excavations but the external 
occipital protuberance is not preserved. 

The paroccipital process projects ventrally to the level of the ventral edge of the 
condyles (pl. 4, fig. 1) asin Okapia. The basioccipital region has a pair of anterior 
occipital swellings between which the bone surface is concave, a median keel begins 
at the anterior end of this concavity and continues on the basisphenoid (pl. 4, fig. 2). 
The lateral face of the basioccipital is concave, this concavity giving way anteriorly 
to the paired basilar tubercles. The occipital-basisphenoid suture is closed. In 
Okapia the anterior swellings of the occipital condyles are much stronger than in 
Zarvafa and the median keel is lost ; in contrast a median depression runs posteriorly 
from the basioccipital—basisphenoid suture. The basilar tubercles are stronger and 
more elongate in Okapia than in Zarafa. The tubercles of the basioccipital provide 
insertion for the rectus capitis ventralis muscle which acts to flex the head downwards. 

Sphenoid. The posterior region of the orbitosphenoid is concave with the optic 
foramen lying at its posteriorend. Behind the optic foramen is a large foramen at the 
base of the alisphenoid. This foramen results from the fusion of the foramen 
rotundum and the foramen lacerum anterius (Colbert 1933) and through it emerge 
cranial nerves III, IV, VI and part of V, it is here referred to as the foramen 
rotundum. Behind the foramen rotundum the pterygosphenoid is produced as a 
ventral process (pl. 2) with convex lateral and concave medial faces. The ridge 
runs posteriorly from the posterior edge of the pterygosphenoid and forms the medial 
wall of the formen ovale through which the mandibular branch of cranial nerve V 
emerges. The foramen ovale is elongate in Zarafa as in Okapia and Guiraffokeryx 
but in contrast to the giraffines and sivatheriids in which the foramen is circular 
(Colbert 1935b). Postero-lateral to the foramen ovale a groove runs along the edge 
of the basisphenoid and dorsal to the auditory bulla as far as the eustachian canal 
and the foramen lacerum medius. The basisphenoid is transversely convex with a 
strong median keel fading out anteriorly. The basisphenoid of Okapia does not 
bear a median keel but is otherwise very similar to that of Zarafa. 

Squamosal. In Zarafa the squamosal surface is concave lateral to the foramen 
ovale. The temporal condyle of the glenoid gives way laterally and posteriorly to a 
glenoid cavity. The post-glenoid process is a strong, high, transverse ridge extending 
further laterally than in Okapia or Giraffa. The anterior edge of the glenoid region 
is formed by a strong ridge which begins at the alisphenoid tuberosity and continues 
laterally as far as the zygomatic arch. The squamosal is convex dorsally and con- 
tributes about half of the temporal wall of the skull, it is also produced laterally as 


7 


GEBEL ZELTEN, LIBYA 89 


part of the zygomatic arch. Over the ear region the squamosal forms a strong 
lateral tuberosity which contributes the postero-dorsal third of the external auditory 
meatus. The anterior edge of the tuberosity is produced into the temporal crest 
which runs anteriorly as far as the post-glenoid process. The squamosals of Zarafa 
and Okapia are similar. 

Ear Region. In Zarafa the external auditory meatus is very ventrally situated, 
it is a postero-laterally directed tube formed by the petrosal and squamosal bones. 
The antero-lateral face of the external auditory meatus is concave with a strong hyoid 
process lying lateral to the bulla. 

The bulla has a relatively thick wall, it is almost spherical in shape and is larger 
than that of Okapia. A large bulla is a primitive feature of the giraffids (Colbert 
1938). The inner ear was partly exposed on the left side of the specimen; it is more 
elongate than that of Prolibytheriwm but appears to be similar in the main features of 
its ventro-lateral face. The fossa tensor tympani is very deep as in Prolibytherium. 
The bone surface is swollen postero-ventrally and above the swelling is a shallow 
concavity which leads anteriorly to the hiatus falloppii. These are the only parts of 
the inner ear visible. 

The temporal canal opens between the ear region and the paroccipital process. 
Lateral to this the petromastoid suture runs dorsally between the squamosal and 
occipital regions. The petromastoid forms the postero-lateral part of the nuchal 
crest and has a concave posterior face. 

Mandible. Only the posterior part of the mandible is known in Zarafa. The 
mandibular foramen is very large (pl. 4, fig. 3) and is situated more anteriorly in 
Zarafa than in Okapia. A deep depression runs from the foramen towards the 
condyle and from the ventral edge of the mandibular foramen a shallow groove 
Tuns antero-ventrally, this groove accommodates the lingual nerve and below it the 
face of the mandible is concave as far as the angle which was probably weak. Ventro- 
medial to Mg the surface of the mandible is swollen and convex. The condyle is 
expanded laterally and medially with a slightly curved articular surface as in 
Okapia. The lateral face of the mandible is slightly convex and in the region behind 
M3 the bone surface rises medially, forming a sharp medial ridge. 

The Skull as a whole. The dorsal view of the skull (pl. 3) is dominated by the 
laterally expanded frontals but the extent, to which the lateral expansion of the 
frontals has effected the individual bones of the facial region, is difficult to assess. 
It is likely that the ancestral giraffids possessed a lacrymal fossa similar to that of 
the cervids; this assumption is made more probable by the condition of Proliby- 
theriwm and the concavity in Zavafa may represent a stage in the reduction of the 
fossa, however it is more likely that the expansion of the anterior supraorbital crest 
formed the concavity of the lacrymal. The dorsal expansion of the lacrymal in 
Zavafa may also be a primitive feature as Dremotherium has a large lacrymal bone 
but the lateral expansion of the frontals has probably influenced the lacrymal causing 
it to expand dorsally. The facial region ot Zarafa exhibits some features that are 
certainly primitive; the paired lacrymal foramina, elongate jugal bones, shallow 
maxilla and large maxillary tuberosity are all features found in the cervids and 
palaeomerycids but absent in adult giraffids. 

B 


90 LOWER MIOCENE RUMINANTS 


The main parameters of the gross cranial anatomy in the giraffids were studied by 
Colbert (1938) who used seven features of the skull in an attempt to establish the 
primitive features of Okapia. Owing to the broken nature of the skull of Zarafa 
only four of Colbert’s parameters can be used (table 5). The degree of facial flexion 
is given as the angle between the basipalatal and basicranial axes; this angle is 
similar in Dremotherium, Okapia, Zarafa and Palaeotrvagus microdon and in these 
genera it is less than in advanced giraffids. The degree of facial flexion is usually 
treated as a measure of the evolutionary stage reached by the genus under con- 
sideration and on this basis Zarafa is as primitive as Dremotheriwm or Palaeotragus 
mucrodon. The angle between the basipalatal axis and the line joining the anterior 
edge of the orbit to the anterior border of the M1, indicates that the orbit of Zarafa 
is more anteriorly situated than in the other giraffids except Okapza in which the 
orbit is in a similar position to that of Dremotherium. An anteriorly situated orbit 
is usually regarded as a primitive feature. The nasals are flat in Zavafa and 
Palaeotragus microdon but in the other giraffids and in Dremotheriuwm the nasals are 
more flexed relative to the skull roof and the basipalatal axis. The condition of the 
primitive giraffid skull is discussed below and it is postulated that a wide, flattened 
skull roof is probably primitive for the giraffids. 

In general shape of the skull, position of the ossicones and features of the basi- 


TABLE 4 
Zarafa zeltent. Measurements of the skull and dentition 
The Skull 
M.26670 M.26673 
Height above M3 88 mm 
Postorbital length. (From anterior edge 
of orbit to occipital condyle) 187 mm 
Maximum width of frontals 179 mm 
Maximum width across occipital region 103 mm 
Width of occipital condyles 57 mm 
Maximum height of occipital region 78 mm 77 mm 
The Upper Dentition 
M.26671 M.26672 
Length Width Length Width 
P4 I5 mm 20 mm — + 
M1 19 mm — 21 mm I9 mm 
M2 22 mm 24 mm 23 mm 22 mm 
M3 22 mm 23 mm — -- 
D2 — = 17 mm 8 mm 
Ds — — 18 mm 13 mm 
D4 — — 18 mm I5 mm 
The Lower Dentition 
M.26675 M.26676 M.26677 
Length Width Length Width Length Width 
M2 25 mm 17 mm 
M3 33 mm 17 mm 32 mm I5 mm 


(All dental measurements are maximum.) 


oI 


GEBEL ZELTEN, LIBYA 


ofl 
xhAayof{vAry 


(‘oor = y38u9] [W!—uq) 


off +6 Sor 6S 89 yjS8ue] Iejour-1ejoureid 
0} P[[XeUI JO YSIOY Jo O17 eYy 
ails Ol oll opt o8l s[eseu JO Iopi0q 
Jotiodns pur sixe [eyeTediseq usemzoq a[Suy 
ols 009 028 ofl 028 “TIN JO Iopiog Ior1ezue 
94} OF FIG10 04} Jo espa Joe} oY} Sututol 
oul] pue sixe [e}eledIseq useMmyoq a[suy 
BOL Xe) AY, of of Soxe [elueioIseq pue [eze[ediseq usemyoq o[suy 
off{vsixy UOposaUM *q vrdvyoQ D{VADZY wNAaYoMaA 


(g€6r yraqjog sazye ‘xAayoffysry pure vffony ‘uoposorm snsvmoanjog ‘v1dvyQ 10} sjusWeInseay)) 
Wmayjez v{pAvZ JO SeInyeoy [eIUWeIO ssoIxy 


¢ alavy 


92 LOWER MIOCENE RUMINANTS 


cranial region Zarafa resembles the genus Palaeotragus and in particular the species 
P. microdon. 

Upper Dentition. The deciduous dentition of Zavafa forms a closed series it is 
therefore likely that the permanent cheek teeth also formed a closed series from P2 
to M8. The molars are more brachyodont than those of Palaeotragus, resembling in 
degree of brachyodonty the molars of Palaeomeryx. The enamel is finely rugose and 
the molars are four rooted with the lingual roots fused. 

M! is almost square with the posterior half of the tooth displaced labially relative 
to the anterior half. The parastyle is strong and its labial rib is stronger than that 
of Palaeotragus. The paracone has a strong labial rib, similar to that of Palaeomeryx 
and stronger than that of Palaeotragus. The posterior end of the paracone lies 
lingual to the mesostyle which is the most labial part of the tooth. The metacone of 
M! is the same height as the paracone, its selene has a diagonal orientation on the 
tooth (pl. 5, fig. 1) and owing to the reduction of the labial rib it is more smoothly 
curved than the paracone. A weak metastyle forms the postero-labial corner of the 
tooth. The protocone is stout with a weak labial swelling which lends slight 
angularity to its crescentic shape, the posterior extension of the protocone ter- 
minates in the median valley without meeting the anterior face of the metaconule 
(pl. 5, fig. 1). The metaconule is higher than the protocone, its anterior region 
curves labially between the paracone and the metacone and from the anterior face 
of this region a small crest is produced into the median valley. A conule in the 
an terior fossette joins this crest and also joins the protocone and metacone giving 
an‘h’ shaped wear trace (pl. 6, fig. 1). The metaconule has a stronger labial swelling 
than the protocone and behind this the height of the cusp is rapidly reduced. A 
long narrow accessory crest is produced from the metaconule and runs antero- 
labially to meet the base of the metacone (pl. 5, fig. 1). M1 has strong anterior and 
posterior cingula. The M! of M.26672 (pl. 5, fig. 1) has a strong entostyle in the 
median valley, this arises from the base of the metaconule and does not join the 
protocone. M.26671 (pl. 6, fig. 1) has strong cingula in the median valley region 
but an entostyle is not developed. M?and M8 are similar in the main features of their 
anatomy to M!. 

P4 is three rooted and brachyodont with finely rugose enamel and anterior and 
posterior cingula which do not join as a lingual cingulum (pl. 6, fig. 1). The parastyle 
has a strong labial rib (pl. 6, fig. 2) as in Palaeomeryx but in contrast to Palaeotragus 
in which the labial rib of P4 is feeble. The strong labial rib of the paracone curves 
anteriorly and carries a deep groove on its anterior face. The paracone of the 
Palaeomeryx P4is similar to that of Zavafa but in Palaeotragus the labial rib is reduced 
and the cusp is more compressed transversely than in the other two genera. The 
metacone has a weak swelling posterior to the paracone rib in Zarafa whereas in 
Palaeomeryx the labial rib of the paracone is clearly fused to the metacone rib, a 
groove indicating the line of fusion and in Palaeotragus a single rib is present with 
no posterior swelling. The protocone of the P4is stout and more regularly crescentic 
than in the molars; the anterior region joins the parastyle at an early stage of wear. 
On the posterior region of the protocone a weak accessory crest joins the base of the 
metacone and anterior to this crest a weaker parallel crest runs into the fossette 


GEBEL ZELTEN, LIBYA 93 


but does not join the base of the metacone (pl. 6, fig. 1). This region of the P4 
differs from both Palaeomeryx and Palaeotragus but this crest is probably an individual 
variation of Zarafa. 

D4 is molariform (pl. 5, fig. 1), the parastyle is stronger than in the permanent 
molars with a strong labial rib. The paracone is thicker transversely than in the 
molars and in the anterior fossette there are a number of small conules (pl. 5, fig. 1). 
The mesostyle is stronger than in the molars, remaining as an independent style until 
late in wear. The metacone has a weak labial rib and the metastyle is stronger than 
in M1 or M2. The metaconule of D4 is similar to that of the molars, a strong fold is 
produced from its anterior region into the median valley producing a forked anterior 
wear trace asin the molars. A strong accessory crest is produced from the posterior 
region of the metaconule and runs antero-posteriorly in contrast to the molars in 
which it runs antero-labially. A small entostyle is produced from the antero-lingual 
face of the metaconule into the median valley asin the molars. A cingulum stretches 
over the antero-lingual region of the protocone and a small cingulum covers the 
postero-lingual corner of the tooth. 

D3 is triangular with a single anterior root and a posterior pair. The enamel is 
smooth except on the lingual faces of the paracone and metacone where it is rugose. 
The parastyle is strong, existing as a separate style until late in wear, it lies near the 
anterior end of the tooth and the wear trace of the paracone branches labially to 
meet it. The paracone has a very strong labial swelling with an anterior groove. 
The metacone and its anterior and posterior styles are similar to those of D4 or the 
molars. The protocone is elongate, its anterior region joins the protostyle which 
forms the anterior end of the tooth. A small crest is produced into the fossette 
opposite the parastyle and opposite the paracone a stronger crest is produced 
(pl. 5, fig. 1). The posterior end of the protocone joins the lingual part of the 
metaconule and there is no median valley. The metaconule of D? is similar to that 
of D4, it is crescentic and in the anterior region it is produced between the paracone 
and metacone (pl. 5, fig. 1). A strong crest is produced from the anterior region of 
the metaconule into the posterior fossette, this crest runs posteriorly across the 
base of the metacone terminating near the middle of the fossette. An accessory crest 
is produced from the posterior region of the metaconule, this also runs to the middle 
of the fossette but does not join the anterior crest. A lingual cingulum runs along 
the base of the protocone ending in the middle of the tooth and a short cingulum is 
produced at the postero-lingual corner. 

D? is very heavily worn and few surface features are visible. The parastyle is 
strong as in D2 and joins a weak protostyle anteriorly. The paracone is high and 
more anteriorly situated than in D8, it has a strong labial swelling. The metacone 
is elongate with a weak labial swelling. The protocone is small and its anterior region 
joins the protostyle and the parastyle, behind this is a weak crest asin D3. There are 
three fine accessory crests on the posterior region of the metaconule (pl. 5, fig. 1). D2 
has a weak lingual cingulum which runs around the base of the metaconule and the 
posterior region of the protocone. The anterior region of D2 resembles that of D3 
but the posterior region does not show any molariform features. 

Lower Dentition. The lower dentition of Zarafa is known from a single Mz and 


94 LOWER MIOCENE RUMINANTS 


two third molars. These teeth are identified as Zavafa on the basis of their size, 
giraffoid features, height and enamel features. 

Mg resembles Canthumeryx in height and is lower than Palaeotragus rouenit. The 
mesostylid is weaker than in Canthumeryx or Palaeotragus and the metaconid rib is 
weak (pl. 5, fig. 3). In Palaeomeryx and Canthumeryx this rib is strong but in 
Palaeotragus it consists of a slight swelling of the surface. The entoconid has a 
weaker lingual swelling than in Canthumeryx or Palaeomeryx and resembles 
Palaeotragus. The posterior region of the entoconid is shortened but expands as a 
crest at some distance above the crown (pl. 5, fig. 3); a similar expansion is present in 
P. rouenit (M.8367) but in Canthumeryx the posterior crest is very strong throughout 
itsheight. The posterior fossette opens lingually (pl. 5, fig. 2). The anterior fossette 
is very shallow and widens at its anterior end (pl. 5, fig. 2) ; a similar widening occurs 
in Palaeotragus but not in Canthumeryx. The anterior cingulum is weaker in 
Zarafa than in Canthumeryx and the posterior cingulum is very short and small 
(pl. 5, fig. 2). Mg has no ectostylid. 

The metaconid of Msg (pl. 5, fig. 4) is similar to that of Mg (pl. 5, fig. 2) and is more 
nearly parallel to the axis of the tooth than in Palaeotragus or Canthumeryx. The 
metaconid rib is weak as in Mz and the metastylid is also weak. The entoconid is 
similar to that of Mg but in its posterior region it expands backwards to join the strong 
entoconulid (pl. 5, figs. 4 and 5) thus closing the posterior fossette. The protoconid 
and anterior end of the hypoconid are similar to those of Mz but the posterior end 
of the hypoconid is flattened. 

The accessory column consists of a stout hypoconulid which curves around the 
posterior end of the tooth, its antero-labial end abuts on the posterior end of the 
hypoconid and its lingual end curves anteriorly and joins the entoconulid (pl. 5, 
fig. 5). A strong ectostylid is present in the median valley and a weaker stylid 
stands in the posterior valley. 

The cheek teeth of Zavafa show resemblances to both Palaeomeryx and Palaeotragus 
so that in some respects Zarafa may be regarded as intermediate between these 
genera. The labial ribs of the paracone and parastyle are weaker than is usual in 
Palaeomeryx though slightly stronger than in Palaeotragus. The mesostyle is strong 
in Zarafa as in Palaeomeryx but the smoothly curved general shape of the metacone 
and reduction of the labial metacone rib are very similar to Palaeotragus and contrast 
with Palaeomeryx. The protocones are similar in Zarafa and Palaeotragus and lack 
the strong postero-lingual spur which is present in Palaeomeryx. The cingula are 
more reduced in Zarafa than in Palaeomeryx but less reduced than in Palaeotragus. 
The upper molars of Zavafa are more hypsodont than in Palaeomeryx but are still 
much lower than in Palaeotragus. On the P4 of Zarafa the labial ribs of the paracone 
and parastyle are stronger than in Palaeotragus though weaker than in Palaeomeryx, 
with this exception the P*is very similar in all three genera though a lingual cingulum 
is sometimes present in Palaeomeryx only. 

The lower molars of Palaeomeryx are low crowned and wider relative to their 
length than in Zarafa, Canthumeryx or Palaeotragus. The lingual faces of the lower 
molars carry weak ribs in Zavafa and Palaeotragus whereas in Palaeomeryx these ribs 
are much stronger. A very weak ‘Palacomeryx fold’ is present in M.26675, this fold 


GEBEL ZELTEN, LIBYA 95 


rarely occurs in Palaeotragus but it is usual and often strong in Palacomeryx. The 
lower molars are higher crowned in Zarafa than in Palaeomeryx though lower than in 
Palaeotragus. 

The upper and lower cheek teeth of Zavafa show features in which they resemble 
Palaeotragus and as these features are more advanced than the primitive ruminant 
condition they are interpreted as indicative of true relationship between the genera. 


Post-cranial material. The Gebel Zelten collection includes a considerable amount 
of post-cranial material but owing to the conditions of preservation none of this 
material was found in association with the cranial elements. Specimens may be 
assigned to one or other of the ruminant genera with varying degrees of confidence, 
highest in the case of Zavafa which is the largest ruminant found at Gebel Zelten. In 
cranial features Zarafa is sufficiently like the other palaeotragines for the assumption 
to be made that the post-cranial elements must also show affinities with this group. 


MaTERIAL: B.U.20115—An almost complete right femur. B.U.z0116—A complete 
right tibia. B.U.zo117—-A complete right metatarsal. B.U.zo118—A complete 
left caleaneum. B.U.20119—A right calcaneum. B.U.20120—A right astragalus. 
B.U.20121—A left astragalus. B.U.20122—A left astragalus. B.U.20123—A left 
scapular fragment. B.U.20124—The distal end of a left humerus. B.U.20125—A 
right olecranon region. B.U.20126—The proximal end of a left radius. B.U.20127 
—The distal end of a left radius. B.U.z0128—A fragment of a right metacarpal. 
B.U.20129—An anterior phalange. B.U.20130—A posterior phalange. B.U.20143 
—An anterior phalange. B.U.20144—A posterior phalange. B.U.20145—A pos- 
terior phalange. B.U.20146—The proximal end of a left tibia. B.U.20147—-An 
axis. B.U.20148—An axis. B.U.20149—A seventh cervical vertebra. B.U.20150 
—A thoracic vertebra, probably the eighth. B.U.20151—A fourth lumbar vertebra. 
B.U.20152—A sixth lumbar vertebra. 


The pectoral girdle 
Scapula. The glenoid is shallowly concave and almost elliptical with a deep 
glenoid notch lying postero-lateral to the coracoid process (text fig. 7c). The coracoid 
process is strongly developed and projects further from the body of the bone than 
the tuber scapulae. In Okapia and Giraffa the tuber scapulae is very strongly 
developed and has grown over the coracoid process whereas in Zarafa the tuber 
scapulae is weak, consisting of a swelling lateral to the coracoid process. The surface 
of the tuber scapulae is heavily sculptured as the origin for the biceps brachii muscle. 
The spine of the scapula is shifted anteriorly and the supraspinous region is very 
narrow as in Okapia. The base of the spine indicates that it rises smoothly and an 
acromion process was probably present as in Palaeotragus and in contrast to Okapia 
and Givaffa in which this process is entirely absent. The absence of the acromion 
process appears to be related to the development of the tuber scapulae as in Equus, 
‘Camelus and large species of Bos the acromion process may be lost, in which case 
the tuber scapulae is of a size comparable to that of Givaffa. A strong tuber scapulae 
presumably indicates a greater development of the biceps brachii muscle and 
similarly reduction or absence of the acromion process indicates a reduction in the 
importance of the acromial part of the deltoideus muscle. The infraspinatus region 


96 LOWER MIOCENE RUMINANTS 


is wide with a thickened posterior edge resulting in the concavity of the infraspinous 
fossa, the posterior edge is also concave as in Givaffa. The subscapular fossa is 
concave distally but the subscapular face of the neck is slightly convex. The shape 
of the neck of the scapula indicates that the blade was as elongate as that of Okapza. 
The anterior shift of the spine is also similar to Okapia. 

Humerus. The distal end of the humerus is known from a single badly shattered 
specimen. The coronoid fossa is shallow with a deeply pitted surface and lateral 
to this the bone is expanded as a very strong lateral epicondyle similar to Okapia 
and Giraffa. The lateral condyle is wide with a concave surface and the medial 
condyle is also wide. The olecranon fossa is very deep. The distal end of the 
humerus is similar to that of Okapia and Giraffa. 

Radius. The lateral tuberosity of the radius is weaker than in Okapza or Giraffa 
and the medial tuberosity is concave. These tuberosities provide attachment for 
the ligaments of the elbow and the smaller size of the lateral tuberosity indicates a 
weaker ligament; this is possible in a small relatively light animal such as Zarafa. 
The distal end of the radius has the usual three articular facets. The scaphoid facet 
is relatively wide; a concavity at the anterior end of the facet acts as a stop preventing 
over extension; this concavity is about the same depth in Okapia and shallower in 
Giraffa. The lunar facet has deep anterior and posterior depressions which also act 
as stops. The cuneiform facet is more oblique than the other two facets and its 
postero-medial region consists ofa vertical concavity. The dorsal face of the bone has 
two strong ridges asin Okapia. The shaft of the bone, although incompletely known, 
appears to have been more slender than in Okapia. 

Ulna. The olecranon process of the ulna is the only region preserved. The 
semilunar notch is transversely narrow and the edges of the facet are rounded 
giving it a transversely convex shape which agrees closely with that of Givaffa. In 
Okapia the semilunar facet is transversely plane which greatly restricts the lateral 
mobility of the elbow. The semilunar region is produced disto-laterally as a strong 
process articulating partly with the lateral condyle of the humerus and partly with 
the posterior face of the radius; this facet is similarly developed in Givaffa. The 
olecranon process is short and transversely flattened with a concave medial face. 
The distal end is heavily sculptured for the insertion of the triceps muscle. 

Metacarpal. ‘The facets of the proximal end are similar to those of Okapia and 
on the postero-medial face of the proximal end the surface of the bone is heavily 
sculptured as in Okapia but there is no indication of metacarpal V. The presence of 
this metacarpal is variable in Givaffa (Fraser 1951) and may also have been variable 
in Zarafa. The shaft of the metacarpal is more slender than that of Okapia; its 
cross-section is flattened as is usual in the ruminants, with a deep channel on the 
posterior face to accommodate the flexor tendons. The distal head has the usual 
paired condyles converging slightly as in Givaffa. The keel of the condyle is very 
strong and in the posterior region it extends proximally as a strong ridge over the 
articular face and beyond this onto the body of the bone. The strength of this keel 
resembles the cervid condition. In both Okapia and Guiraffa the condyle is ex- 
panded in the interdigital region which reduces the apparent strength of the keel. 
The distal head of the metacarpal is much wider than the shaft in Zarafa, Givaffa 


GEBEL ZELTEN, LIBYA 97 


and the cervids but in Okapia it is only slightly wider as the shaft is thickened. 

Phalanges. The phalanges are very slender. Their postero-proximal epicondyles 
are very short whereas in Okapia and Giraffa they are elongate, covering about one 
third of the posterior face of the phalange. The interdigital face has a weak tuberos- 
ity in the distal region to which the interdigital ligament attaches. The distal 
articular face consists of a central depression flanked by two expanded areas which 
extend over the end of the bone; this facet is slightly oblique which causes the second 
phalange and hooves to move towards each other when weight is placed on the foot. 

Five phalanges are identified with Zarafa, these include two larger and three 
small ones. The difference in size between these groups is approximately the same 
as the size relationship between the anterior and posterior phalanges of Okapia; 
for this reason the larger are identified as anterior and the smaller as posterior. The 
smaller phalanges will not be described separately with the description of the pelvic 
limb. 


The Pelvic Limb 

Femur. The head of the femur is small relative to the length of the bone; its 
articular surface extends onto the neck and around the lower side of the head as in 
Okapia. The neck of the femur is long and the head is displaced further medially 
than in Okapia or Givaffa. In both Okapia and Giraffa certain tendencies towards a 
graviportal condition of the limbs are evident, these tendencies are most apparent 
in the rotation of the articulations into the line of the shaft. The greater displace- 
ment of the articulations or curvature of the shaft of the limb bones in Zarafa 
indicates a lighter animal. The trochanter minor is weak and is not displaced as 
far medially as it is in Okapia or Giraffa; as a result the trochanteric ridge appears 
stronger in Zarafa than in the extant giraffids. 

The distal region of the femur is of the usual ruminant pattern. On its anterior 
face the medial ridge is high and expanded but is less swollen than that of Okapia 
or Givaffa, this indicates that the ‘stifle joint’ was less effective than in Okapia or 
Givaffa as expected in a smaller lighter animal (Shuttleworth 1943). The medial 
and lateral epicondyles are very strong but are less transversely expanded than those 
of Okapia. The shaft of the femur is slender and slightly curved anteriorly (posterior 
face concave) as in the medium sized cervids and in contrast to Okapia and Giraffa 
in which the shaft is straight and relatively stout. The supracondyloid fossa is 
more elongate than in Okapza, this is probably due to the generally narrower nature of 
the distal region in Zarafa. 

The femur of Zavafa is much more slender than that of Okapia and both extremities 
are narrower. The curvature of the shaft indicates a lightly built animal and 
features such as the positionof thetrochanter minorare similarto the cervidcondition. 

Tibia. The proximal head of the tibia is narrow transversely as in the cervids 
and in contrast to Okapia or Giraffa in which the head is relatively wide. The 
cnemial crest is high and blends gradually into the shaft over the proximal quarter 
of its length; this crest is similar in the medium sized cervids but in Okapia it occupies 
the proximal third of the anterior face. The antero-proximal region of the cnemial 
crest forms a large triangular tuberosity bounded laterally by the sulcus muscularis 


98 LOWER MIOCENE RUMINANTS 


and medially by a shallow depression through which the middle patellar ligament 
passes. A small tubercle is produced posterior to the spine, this is similar to that of 
Okapia and provides attachment for the posterior cruciate ligament. 

The distal end of the tibia is much narrower in Zarafa than in Okapia and in general 
features it resembles the cervid tibia. The shaft is slightly curved posteriorly as in 
the cervids and in contrast to Okapia in which the shaft is straight. The tibia of 
Zarafa is relatively shorter than that of Capreolus but longer than that of Okapia or 
Giraffa. Itissimilarinits main features to the tibia of Givaffa whichis more primitive 
than that of Okapia. 

Calcaneum. The tuber calcis is very long and similar to Capreolus or Palaeomeryx 
whereas in Palaeotragus and Samotherium it is slightly shortened and in Okapia and 
Giraffa it is extremely shortened. The tuber calcis is more flattened than in Okapia. 
The posterior face of the sustentacular process is plane whereas in Okapia and 
Samotherium it is concave. The lateral face of the calcaneum bears an area of heavy 
sculpturing occupying most of the antero-proximal region, posterior to this is a small 
oval facet to which the lateral ligament of the ankle attaches. The fibular facet is 
of the usual primitive form with a raised convex posterior region and a concave 
anterior region as in Palaeomeryx and in contrast to Okapia in which this facet is 
specialized by the loss of the anterior region. The facet in Zarafa indicates that the 
fibula was probably similar to that of Capreolus. The sustentacular facet is wide 
and transversely convex, it does not show any reduction of the proximo-medial 
corner, such as is found in Okapia and Giraffa as a specialization facilitating greater 
flexion of the ankle. The calcaneum is generally more like that of the cervids than 
the extant giraffids, this is however partly due to the specialization of the ankle in 
Okapia and Giraffa. 

Astragalus. This is more elongate than in Okapia or Givaffa and compares very 
closely in all its main features with the astragalus of Palaeomeryx. 

Metatarsal. The proximal facets of the metatarsal are similar to those of Okapia. 
A deep notch lies on the lateral edge of the bone between the facets, this probably 
housed metatarsal V which appears to have been well developed in contrast with the 
extant giraffids in which it is represented as a thin ribbon of bone, entirely fused to 
the lateral face (Fraser 1951). A strong tubercle lies between and medial to the 
facets, this is metatarsal II and is stronger than in Givaffa or Okapia; it continues on 
the medial face as a wide ribbon of bone fused to the shaft and continuing much 
further distally than in Givaffa. 

The shaft of the metatarsal is very long and slender in Zarafa, it has a deep cross- 
section as in Givaffa, Samotherium and Palaeotragus, this is narrower transversely 
than in Okapia. The two condyles of the distal extremity are similar to those of 
Givaffa but the ridges of the condyles are stronger as on the metacarpal. A deep 
channel runs down the anterior face of the bone, this channel is open for its whole 
length as in Okapia, Givaffa and the bovids whereas in the cervids the channel is 
roofed over in the distal region. 


Vertebrae 
Axis. The axis of Zarafa is smaller and more elongate than that of Okapia. The 


GEBEL ZELTEN, LIBYA 99 


neural spine has a high posterior tubercle (text fig. 2a) from which it slopes down- 
wards anteriorly and projects over the odontoid process as in Okapia. The odontoid 
process is similar to that of Givaffa and the anterior articular facet has a depression 
near to and around the base of the odontoid process as in Givaffa but in contrast to 
Okapia in which the facet blends into the odontoid process. The anterior articular 
facet slopes almost vertically as in Giraffa. The intervertebral foramen (text fig. 
2a) is in the same position as that of Okapia, it has a deep postero-ventral channel 
which joins it to the anterior channel of the vertebrarterial canal. This canal begins 
near the middle of the bone and emerges on the posterior face, dorso-lateral to the 
articulation. The posterior articular process is less pronounced than in Okapia, its 
articular facet is almost circular and faces postero-ventrally. The transverse 


Fic. 2. The vertebrae of Zavafa. (Half natural size.). (A) Lateral view of the axis 
(B.U.20148). (Bs) Lateral view of the seventh cervical vertebra (B.U.20149). (c) Lateral 
view of the fourth lumbar vertebra (B.U.20151). (bp) The anterior face of the fourth 
lumbar vertebra (B.U.20151). (E). Anterior face of the sixth lumbar vertebra (B.U.20152). 
(F) Lateral view of the eighth thoracic vertebra (B.U.20150). a: neural spine. b: 
posterior tubercle. c: posterior articular process. d: odontoid process. e: inter- 
vertebral foramen. f: vertebrarterial canal. g: transverse process. h: anterior 
process. j: nutrient foramen. k: tubercular facet. 1: posterior facet for the head of 
the rib. m: anterior facet for the head of the rib. n: tuberosity. 


100 LOWER MIOCENE RUMINANTS 


process is more slender than that of Okapia and is more dorsally situated; lying at 
the same level as the top of the centrum (text-fig. 2a). The posterior articular face 
of the centrum is concave as in Okapia; and in Zarafa it is more nearly vertical than in 
Okapia. 

Cervical vertebra. The seventh cervical vertebra (text fig. 2b) is similar to that of 
Okapia with no signs of the specialization found in Givaffa (Lankester 1908). The 
centrum is thicker than in Okapia and both anterior and posterior articulating faces 
of the centrum are more nearly vertical in Zavafa than in Okapia; in this feature the 
vertebra is similar to that of Givaffa. The anterior articulating processes are more 
widely divergent than in Okapia but the articulating facets are orientated at the 
same angle in both genera. The posterior articular processes are lateral only with no 
indication of the medial articulation such as occurs in Okapia (Lankester Ig10). 
The facets are elongate which indicates that there was considerable freedom of move- 
ment of the lower neck region. 

Thoracic region. A single thoracic vertebra (B.U.20150) agrees closely with the 
eighth thoracic vertebra of Okapia. The anterior face of the centrum is shallowly 
convex and the facet extends ventrally as it does in Okapia. The facet for the head 
of the rib (text fig. 2f) is more closely blended with the centrum face than in Okapza. 
The ventral ridge is strong with a tubercle in the postero-dorsal corner of the concave 
lateral face (text fig. 2f), this is equally well developed in Okapia. The posterior face 
of the centrum is concave with the facets for articulation with the rib situated high 
up at the dorso-lateral corners of the face (text fig. 2f). The transverse process is well 
developed with a tubercular facet running antero-dorsally from its ventro-lateral 
region. The mamillary process is only weakly developed and is more laterally 
situated than in Okapfia. Both anterior and posterior articular processes are 
deformed as only the left side is developed in each case and the facets on this side 
have undergone compensatory size increases. The neutral spine is very slender and 
its posterior region is only slightly thickened; the spine was probably higher than in 
Okapia and more posteriorly inclined. 

Lumbar vertebrae. The fourth lumbar vertebra (B.U.20151) is more elongate than 
in Okapia or Giraffa with a strong ventral ridge and ventro-lateral concavities as in 
Okapia. A large nutrient foramen lies lateral to the ventral ridge, just anterior to 
the middle of the centrum (text fig. 2c); in Okapia and Givraffa many small foramina 
are found in this region. The anterior face of the centrum is shaped as shown 
(text fig. 2d) and the posterior face is expanded slightly transversely as in the other 
giraffids. The anterior articular process is strong and high with a medially concave 
articular facet as is usual in the lumbar region of the ruminants. The posterior 
articular process is short and resembles Giraffa as it faces ventro-laterally, rather than 
laterally as it does in Okapia. The posterior articular process is not produced as far 
posteriorly as it is in Okapia. The neural spine is stout and high; it is expanded 
anteriorly in the distal region which is also thickened and has an excavated surface 
for the insertion of the longissimus dorsi muscle. 

The sixth lumbar vertebra (B.U.20152) is free with a transversely expanded 
centrum (text fig. 2e) bearing a strong ventral ridge in the anterior region only. 
The anterior articular process has an elongate articular facet directed postero- 


GEBEL ZELTEN, LIBYA IOI 


ventrally as in Givaffa and not ventrally as in Okapia which indicates a greater 
freedom of movement at this joint in Zavafa and Giraffa than in Okapia. The 
transverse process (text fig. 2e) is slender and slopes slightly ventrally as in Givaffa. 
The facet of the posterior articular process is elongated antero-posteriorly but is not 
as long as that of Givaffa. The neural spine is more anteriorly situated in Zavafa 
than in Givaffa and the posterior part of the centrum is slightly elongated. 

Functional Interpretations. The forelimb and vertebral column of Zarafa are 
poorly known and it is not possible to make any meaningful functional interpreta- 
tions of these regions. Fortunately the hind-limb is almost completely known and 
it has been used to assess the degree of cursorial adaptation attained. 

The main recent study of functional features of the limbs of mammals is that of 
Smith and Savage (1956) who in their section on the hind limb deal only with the 
muscles originating on the pelvis. In Zarvafa the pelvis is not known and therefore 
this group of muscles cannot be studied but the mechanical advantage of the biceps 
femoris and semi-tendinous muscles, which insert on the cnemial crest, can be 
estimated using the formula: 


Mechanical advantage of biceps __ Height of cnemial crest 
femoris and semitendinous muscles ————‘ Total length of lower leg 


In this equation it is assumed that the femur and pelvis are rigid which they are 
not; but the accuracy of the figures obtained is sufficiently high as the formula is 
used for comparative purposes rather than to obtain absolute measurements. The 
height of the cnemial crest of the tibia is measured from the posterior face of the tibial 
spine and the length of the lower leg is measured vertically from the knee to the 
ground. 

If the mechanical advantage of the locomotory muscles is high then a slow power- 
ful action is indicated as found in graviportal animals. A low mechanical advantage 
of the locomotory muscles indicates a weak but rapid action and is characteristic 
of cursorial animals, thus the mechanical advantage of a group of muscles may be 
used to measure the degree of cursorial adaptation attained. Table 7 indicates that 
Givaffa has a lower mechanical advantage for the biceps femoris than the other 
genera and Givaffa is more cursorially adapted than these genera. In degree of 
cursorial adaptation, as measured using the muscles inserting on the cnemial crest 
Zarafa lies between Okapia and Capreolus. 

The mechanical advantage of the gastrocnemius muscle which inserts on the end 
of the tuber calcis can be estimated using the formula: 


Mechanical advantage of —— Length of tuber calcis 


gastrocnemius muscle Length of ankle and pes 


As may be expected Givaffa again exhibits considerably greater cursorial adaptation 
than the other genera and Zarafa again lies between Okapia and Capreolus (table 7). 

The osteological features of Zavafa indicate a lightly built animal and this is borne 
out by features of the limbs which taper rapidly and are very slender, thus the low 
degree of cursorial adaptation, as measured from the mechanical advantages of 
the muscles, must be interpreted as a primitive feature of Zarafa. 


102 LOWER MIOCENE RUMINANTS 


TABLE 6 


Measurements of Zavafa zelteni post-cranial elements 
Vertebrae 
B.U.20147 B.U.20148 B.U.20149 B.U.20150 B.U.20151 B.U.20152 


Length of centrum 69 mm 65 mm 32 mm 34 mm 47 mm 37 mm 
Total height of vertebra 63 mm 68 mm 72mm 131 mm oI mm 47 mm 
Depth of centrum 20 mm 19 mm 23 mm 24 mm 23 mm 21 mm 
Width of anterior end 
of centrum 52 mm 49 mm I9 mm 28 mm 35 mm 37 mm 
Width of posterior 
end of centrum 35 mm 34 mm 34 mm 36 mm 39 mm 48 mm 
Scapula 
B.U.20123 
Width ot neck of scapula (Min.) 36 mm 
Depth of neck of scapula (Min.) 19 mm 
Width of glenoid (Ant-post) 47 mm 
Depth of glenoid (Transverse) 39 mm 
Humerus 
B.U.20124 
Distal end 
Width across epicondyles 59 mm 
Antero-posterior depth of 
distal articular surface 27 mm 
Radius 
B.U.20126 B.U.20127 
Width of proximal articular surface 49 mm 
Depth of proximal articular surface: 
Minimum 29 mm 
Maximum 18 mm 
Width of distal articular surface 44 mm 
Depth of distal articular surface 29 mm 
Metacarpal 
B.U.20128 
Length 317 mm 
Width of distal end 46 mm 
Depth of distal end 25 mm 
Phalanges 
B.U.20129 B.U.20143. B.U.20144 B.U.20145 B.U.20130 
Length 70 mm 68 mm 63 mm 62 mm 58 mm 
Width of proximal end 21 mm 21 mm 20 mm 19 mm 20 mm 
Depth of proximal end 23 mm 25 mm 23 mm 24 mm 23 mm 
Width of distal end 16 mm 18 mm 16 mm 16 mm 17 mm 
Depth of distal end 14 mm 15 mm I2 mm 13 mm 12mm 
Femur 
B.U.20115 
Total length (Maximum) 341 mm 
Width of proximal end 84 mm 
Depth of articular head 36 mm 
Width of distal end 66 mm 
Depth of distal articular head: 
Maximum 83 mm 
Minimum 58 mm 


GEBEL ZELTEN, LIBYA 103 


TABLE 6 (cont.) 


Tibia 
B.U.20116 B.U.20146 
Length 349 mm — 
Width of proximal end 68 mm 69 mm 
Depth of proximal end 76 mm 72 mm 
Width of distal end 46 mm — 
Depth of distal end 35 mm — 
Calcaneum 
B.U.20118 B.U.20119 
Total length 108 mm 115 mm 
Length of tuber calcis 74 mm 76 mm 
Width across sustentaculum 34 mm 32 mm 
Depth of tuber calcis 28 mm 27 mm 
Maximum depth of bone 41 mm 42 mm 
Astragalus 
B.U.20120 B.U.2012t B.U.20122 
Maximum length 49 mm 41 mm 53 mm 
Minimum length 40 mm 40 mm 41 mm 
Width proximally 29 mm 30 mm 32 mm 
Width distally 29 mm 29 mm 30 mm 
Maximum depth 23 mm 23 mm 25 mm 
Metatarsal 
B.U.20117 
Length 349 mm 
Width of proximal end 39 mm 
Depth of proximal end 41 mm 
Width of distal end 42 mm 
Depth of distal end 29 mm 
TABLE 7 
Measurements used for functional interpretation of the Zavafa hind limb 
Givaffa Okapia Zraafa Capreolus 
Height of cnemial crest of tibia 10-5 mm 5°7 mm 6-5 mm 3°5 mm 
Total length of lower leg 179°0 mm 87:5 mm 87-0 mm 45°5 mm 
Length of tuber calcis 15-9 mm 8-6 mm 8-7 mm 5-0 mm 
Length of ankle and pes II0‘o mm 51-0 mm 50°0 mm 26:0 mm 
Mechanical advantage of biceps 
femoris muscle 0-059 0:065 0:075 0:077 
Mechanical advantage of 
gastrocnemius muscle 0-163 0-166 0-174 o-192 


Family SIVATHERIIDAE nov. 


Diacnosis: Large giraffoids with strongly expanded frontal bones and pneumatized 
skull roof. On the frontal and parietal bones a pair of large, flattened, variably 
branched ossicones is produced. A great increase in overall body size occurs in 
advanced genera but elongation of the limbs and neck does not occur. 


104 LOWER MIOCENE RUMINANTS 


REMARKS: This group has previously been treated as a subfamily of the Giraffidae 
but the presence of Prolibytherium and Zarafa in deposits of early Miocene age 
indicates a division which extends back into the Oligocene. A more natural grouping 
results if the Palaeotraginae and Giraffinae are grouped together in the Giraffidae 
and the Sivatheres are placed in a separate family the Sivatheriidae. 


Genus PROLIBYTHERIUM Arambourg 1961 


Diacnosis: A primitive sivatheriid of small size. The cranium is narrow and 
exhibits very little facial flexion. The frontals support large, aliform ossicones which 
extend anteriorly in the supraorbital region and posteriorly over the parietal and 
occipital region. The occipital condyles are large with very thickened bone. A 
lacrymal fossa and paired lacrymal foramina are present. 


Prolibytherium magnieri Arambourg 1961 


Diacnosis: As for genus. 


Ho.otype: A cranium with badly shattered ossicones, described by Arambourg 
(196Ia). 

LOCALITY AND HORIZON: The material is all collected from the Lower Miocene 
(Burdigalian) deposits of Gebel Zelten, Libya. 


REMARKS: Specimens in l'Institut de Paléontologie, Paris, include dentitions of 
Prolibytherium but these were not found with the type material and were not described 
by Arambourg. 


MATERIAL: Specimens in l'Institut de Paléontologie are defined by capital letters. 

M.21901 An almost complete skull; the ossicones, cranium and left maxilla 

are complete. The upper dentition is heavily worn and lacks P3. 

M.21899 A right mandible with heavily worn dentition. 

M.26678 An endocranial cast that was dissected out of a skull. 

M.26679 A fragment of cranium, with ossicones and bearing the only large 

lacrymal fragment. 

M.26680 An edentulous mandible which has a complete diastema. 

M.26681 An isolated lower third molar, ightly worn. 

ipeie AS An almost complete mandible with Pz to Mg exhibiting slight wear. 

JPME, 183. A mandibular fragment with almost unworn M; to M3. 

P.M. C. A mandibular fragment with heavily worn M;. The P, was dis- 
placed to the side during life and is thus virtually unworn. 


P.M. D. A mandibular fragment with heavily worn M, to M3. 
PME: Pg and P4, both lightly worn. 
PME: A badly shattered M3. The paracone and antero-labial region is 


missing but the metacone is complete. 
B.U.20175 A right mandible with heavily worn P3 to M3. 
B.U.20176 A cranium with the external auditory meatus preserved. 


GEBEL ZELTEN, LIBYA 105 


THE SKULL AND DENTITION 

The Skull. The skull roof is entirely covered by large ossicones (pl. 7) which are 
completely fused to the frontal and parietal bones without any visible suture. The 
facial region is incompletely known as the premaxillary and nasal bones are not 
preserved and the jugalis known from a single small fragment. A complete lacrymal 
has not been discovered but several large fragments of the lacrymal are known. 
With these exceptions the cranial elements are almost completely known from well 
preserved specimens. 

Maxilla. The maxilla of M.2tgor is broken near the postero-labial alveolus of M3, 
the break continuing antero-dorsally along the maxillary jugal suture (text fig. 3a). 
The maxilla is complete dorsally as far as the maxillary-nasal suture and anteriorly 
it is broken along what is probably the maxillary-premaxillary suture (pl. 8). The 
lateral surface of the maxilla is convex with a feeble facial crest which joins the 
weak facial tuberosity at its posterior end. The infraorbital foramen is slightly 
larger than the lingual alveolus of P%; it is deeply inset below the curve of the 
maxilla above P? as in Sivatherium and Capreolus (text fig. 3b). In Okapia and 
Givaffa the infraorbital foramen is more anteriorly situated than in Prolibytherium; 
this difference may be due to the expansion and increased height of the maxilla in 
the extant giraffids. The molars and P4 have a diagonal orientation relative to the 
main contours of the maxilla which results in strong juga alveolaria on the surface 
of the maxilla (pl. 8). Above the facial tuberosity the surface of the maxilla is 
deeply concave indicating the presence of a lacrymal fossa (pl. 8), this region agrees 
closely with that of Capreolus and differs from Okapia and Giraffa. Above this 
region the maxilla forms the antero-ventral border of the preorbital vacuity (text 
fig. 3a), this edge is similar to that of Capreolus (text fig. 3b). 

The palatine process of the maxilla is shallowly concave with the median suture 
raised above the bonesurface. The anterior palatine foramen is level with the antero- 
lingual corner of M2 and the palatine groove runs anteriorly from it (pl. 9). Behind 
M3 is a large maxillary tuberosity as in Palaeomeryx and Zarafa. 

The maxilla of Prolibytherium is very shallow in the region under the orbit, as in 
Zarafa. The maxillae of Prolibytherium and Capreolus agree closely in shape (text 
fig. 3b) ; this agreement is less close in the posterior region where the maxilla is reduced 
in Capreolus and the jugal is expanded ventrally. 

Lacrymal. ‘The orbital face of the lacrymal is concave and the border of the orbit 
is sharp. Paired lacrymal foramina are present, the dorsal foramen lies behind 
the lacrymal tubercle and in Prolibytheriwm both foramina lie behind the edge of the 
orbit whereas in Capreolus they are situated on the edge of the orbit. The anterior 
face of the lacrymal is very concave and the bone is thin ventrally. Although the 
ventral part of the lacrymal is not known, the concavity of the dorsal region and 
the reduction in thickness of the bone agree with the concavity of the dorsal part of 
the maxilla and indicate the presence of a deep lacrymal fossa. A lacrymal fossa is 
absent from all giraffids and the other sivatheriids but is present in cervids and in 
some bovids. In the cervids this fossa houses the facial gland which produces a 
secretion used in territorial marking. The establishment and maintenance of a 
territory involves a certain amount of intraspecific combat and the occurrence of this 


Cc 


106 LOWER MIOCENE RUMINANTS 


in Prolibytherium is also indicated by the large ossicones. The presence of a lacrymal 
fossa in Prolibytheriwm the cervids and Dremotherium could result from parallel 
development but in this instance it is more likely that its presence is a primitive 
feature. 

Jugal. A fragment of the jugal is preserved attached to the maxilla (text fig. 3a). 
The dorsal edge of this fragment runs postero-ventrally and is probably the suture with 
the lacrymal. The flattened antero-dorsal face of the jugal is continuous with the 
lacrymal fossa. 

Palatine. The palatine is transversely concave and the depth of this concavity 
increases posteriorly (pl. 9). The anterior palatine foramen opens on the anterior 
suture. The median suture is slightly raised as on the maxilla and the posterior 
end of the palatine is deeply indented forming the edge of the pterygo-palatine fossa 
(pl. 9); here the bone is vertical with a lateral face which is continuous with the 
maxillary tuberosity. The lateral face of the palatine is penetrated by the posterior 
palatine foramen which is similarly situated in Capreolus but is higher in Okapia. 


b 


Fic. 3. The maxilla of Prolibytherium (B.M.21901). (Half naturalsize). (a) Lateral view 
of the maxilla. a: maxillary-premaxillary suture. b: maxillary-nasal suture. c: 
border of preorbital vacuity. d:lacrymalfossa. e:fragmentofjugalbone. f:maxillary- 
jugal suture. g: facial tuberosity. h: infraorbital foramen. (B) Comparative outlines 
of the maxilla in Pvolibytherium and Capreolus. Prolibytherium —————————: 
Capreolus ---------------- 


GEBEL ZELTEN, LIBYA 107 


Frontal. The orbital region of the frontal is concave and the orbital opening of 
the supraorbital canal is in the dorsal region of this concavity; probably as a result 
of the thickening of the bone, this opening is situated more medially than in Okapia 
or Givaffa. From its orbital opening the supraorbital canal runs dorso-medially for 
a short distance before turning sharply anteriorly, it continues in this direction as 
far as the dorsal face, thus opening much more anteriorly than is usual in the 
ruminants. The medial edge of the supraorbital process forms a strong ridge which 
continues medially as far as the alisphenoid tuberosity. The temporal region of the 
frontal is convex dorso-ventrally and blends into the ossicone in its dorsal region. 
The supraorbital foramen is anterior to the highest part of the orbit and the deep 
supraorbital groove runs anteriorly from the foramen to the lateral end of the 
frontal-nasal suture (text fig. 4). The supraorbital crest is formed by the thickening 
of the frontal along the edge of the orbit. Behind the supraorbital foramen the 
bone forms a triangular depression bounded antero-laterally by the supraorbital 
crest and medially by the median suture which is raised into a crest running posteriorly 
as far as the frontal eminence (text fig. 4). 

Parietal. The lateral face of the parietal is convex and the dorsal region fuses 
with the ossicone. In front of the occipito-parietal suture the dorso-lateral face of 
the bone is concave with a strong parietal crest which blends into the ossicone 
anteriorly. The opening of the large temporal canal is visible on the broken edge of 
the bone (pl. 7). 

Ossicones. The ossicones fuse completely with the expanded frontal and parietal 
bones, they are large and aliform and have been arbitrarily divided into anterior 
and posterior palmations for the purposes of description (text fig. 4). From the 
frontal eminence a strong crest runs antero-laterally forming the posterior edge of 
the triangular supraorbital concavity of the frontal (text fig. 4); this crest continues 
laterally as the leading edge of the anterior palmation. Another crest runs postero- 
laterally from the frontal eminence and forms the thick posterior edge of the posterior 
palmation. Lateral to these crests the ossicones become much thinner with concave 
dorso-lateral faces. 

The dorsal and ventral surfaces of the ossicone bear a large number of fine, 
radiating grooves (pl. 7). Immediately dorsal to the supraorbital process is a small 
foramen on the leading edge of the anterior palmation, a deep groove originates from 
this foramen and runs postero-laterally across the lateral concavity of the ossicone, 
giving off many smaller branches over the surface. 

The ventral surface of the ossicone is convex antero-posteriorly and shallowly 
concave transversely. A large groove begins postero-lateral to the supraorbital 
process and runs postero-laterally nearly to the edge of the ossicone where it forks, 
one branch follows the lateral edge of the anterior palmation and the other follows 
the edge of the posterior palmation. Above the glenoid cavity a large foramen, at 
the base of the ossicone, gives rise to a deep groove which divides into many fine 
grooves radiating over the lateral surface of the ossicone. A medial foramen is 
situated above the occipital region, at the base of the ossicone, lateral to this is a 
stout column beyond which is a larger lateral foramen (pl. 10, fig. 2) many fine 
grooves radiate from this foramen. 


108 LOWER MIOCENE RUMINANTS 


Occipital. The dorsal surface of the supraoccipital region is convex as far as the 
nuchal crest. In the palaeotragines the supraoccipital region is reflected over the 
condyles but in Prolibytherium it 1s vertical or slopes slightly anteriorly as in Capreolus. 
The mastoid process forms the lateral wings of the nuchal crest and the supra- 
occipital forms the dorsal part of the crest (pl. 10, fig. 2). The medial edge of the 
mastoid foramen is formed by the occipital bone. On the posterodorsal face of the 
supraoccipital region are paired depressions providing insertion for the semispinalis 
capitis muscles—the chief extensors of the head and neck. The external occipital 
protuberance lies medio-ventral to these pits (pl. Io, fig. 2), its surface is deeply 
sculptured (pl. 10, fig. 2) for attachment of the nuchal ligament. The ventral part of 
the external occipital protuberance is produced ventrally as a strong median crest. 
The occipital condyles have sharp keels on their lateral faces (pl. Io, fig. 1). The 
condyles are set very close to the skull; they are relatively large and the bone is 


Fic. 4. Dorsal view of the ossicones of Prolibytherium (B.M.21g901) (One sixth natural 
size.). a:posteriorpalmation. b:anteriorpalmation. c—d: cross-section of the ossicone. 
e: position of frontal eminence. f: supraorbital groove. g: fronto-nasal suture. h: 
dorsal opening of supraorbital canal. x-y: cross-section of the ossicone. 


GEBEL ZELTEN, LIBYA 109 


greatly thickened. The foramen magnum is small relative to Okapia or Giraffa 
and the incisura intercondyloidea, which is strong is the giraffids, is reduced to a small 
notch on the ventral edge of the foramen magnum. 

The basioccipital region is extremely thickened with a pair of large anterior 
swellings produced from the anterior region of the occipital condyles (pl. 10, fig. 1). 
Weaker swellings are present in Okapia and Givaffa. Mead (1906) found that these 
anterior swellings are present in all horned ruminants, in which they act to strengthen 
the atlanto-occipital joint during combat and according to Webb (1965) they also 
act to prevent over flexion of the joint during grazing. The great weight of the 
ossicones in Prolibytheriwm would increase the requirement for such swellings for 
both functions. The median keel originates at the anterior end of the basioccipital 
and runs posteriorly, merging into the condyles between the swellings (pl. 10, fig. 1). 
Paired basilar tubercles lie in front of the swellings (pl. Io, fig. 1) ; they have sculptured 
surfaces and fade anteriorly into slight concavities. The tubercles provide insertion 
for the rectus capitis ventralis muscles which act to flex the head and to incline it 
laterally. The eustachian canal follows the lateral edge of the basioccipital region. 

The paroccipital process is stout, with a thickened anterior face providing origin 
for the digastric muscle. The posterior face of the process is concave and is the area 
of insertion of the rectus capitis lateralis muscle. The anterior face of the process is 
sculptured for attachment to the meatus region of the squamosal. 

Sphenoid. The optic and ethmoid foramina are more ventrally situated in 
Prolibytherium than they are in Givaffa or Okapia and the ethmoid foramen is more 
anteriorly situated in Prolibytherium. Behind the optic foramen is the large foramen 
rotundum (pl. ro, fig. 1) and behind this is the foramen ovale which is circular in 
Prolibytherium, as in Giraffa and Sivatherium and in contrast to Zarafa and the other 
palaeotragines in which it is oval. The orbitosphenoid is concave in front of the 
optic foramen. The alisphenoid has a plane lateral face and a concave ventral face, 
with a strong alisphenoid tuberosity at the junction of these faces. The pterygoid 
groove follows the edge of the basisphenoid ventro-medial to the foramen rotundum 
and the foramen ovale, it is roofed over at its posterior end by the temporal process 
of the sphenoid; this process has two longitudinal grooves on its surface, the medial 
one of these carries the eustachian tube and the other is continuous with the 
pterygoid groove. Only the posterior end of the pterygo-sphenoid is preserved. 
The basisphenoid is cylindrical widening slightly at the posterior end, near the suture 
with the basioccipital (pl. 10, fig. 1). 

Squamosal. The cranial surface of the squamosal is overlapped by a downward 
process of the parietal and is not visible. The lateral face is convex and the post- 
glenoid foramen is directed dorso-laterally. In front of the postglenoid foramen the 
bone surface is convex as far as the squamosal-alisphenoid suture. The glenoid 
cavity is transversely convex and the postglenoid process is slightly concave on its 
anterior face, the process is elongate transversely as in Zarafa (pl. Io, fig. 1). The 
temporal condyle is shallowly convex and its anterior edge forms a strong crest as far 
as the alisphenoid. The bone is concave medial to the glenoid cavity and a groove 
runs postero-laterally around the postglenoid process. The zygomatic arch is missing 
as the bone is broken immediately lateral to the glenoid cavity. The lateral 


110 LOWER MIOCENE RUMINANTS 


tuberosity of the squamosal is stronger than in Okapzia, it has a concave posterior 
face which is deeply sculptured. The antero-ventral face has a deep groove running 
laterally across it, this is the postero-dorsal part of the tube of the external auditory 
meatus. 

Petrosal. The tympanic bulla is not preserved but the region which surrounded 
the bulla indicates that it was about the same relative size as that of Okapia or 
Zarafa. The petrosal contributes most of the meatus, with a small contribution from 
the squamosal in the postero-dorsal region. The meatus opens laterally as in Okapia 
or Givaffa and in contrast to Capreolus in which it slopes dorso-laterally from the 
bulla. The stylomastoid foramen lies postero-lateral to the meatus. Antero- 
ventral to the meatus is a strong hyoid process. 

The inner ear is figured in ventro-lateral and medial views (text figs 5a and b). 
In ventro-lateral view (pl. 11, fig. 3) the most prominent region is the fossa tensor 
tympani, a large deep depression housing the tensor tympani muscle which inserts 
on the malleus. Anterior to this fossa is a deep, narrow channel, the hiatus falloppii, 
which carries the superficial petrosal nerve, a branch of cranial nerve VII. Posterior 
to the fossa tensor tympani is a small foramen which is continuous with a deep, 
ventrally running groove—the aquaeduct falloppii, this in turn is continuous with the 
stylomastoid foramen (text fig. 5a). Cranial nerve VII enters the petrosal via the 


A 


Fic. 5. The right petrosal of Pyrolibytherium (1:25 x natural size). (A) Ventro-lateral 
view. (B) Dorso-medial view. a: lateral tuberosity of the squamosal bone. b: aquae- 
duct falloppii. c: fossa tensor tympani. d: hiatus falloppii. e: fenestra ovalis. f: 
fenestra rotunda. g:aquaeduct cochlea. h:chordatympani. i: groove of the foramen 
lacerum posterius. j: petrosal wall of the stylomastoid foramen. k: squamosal-petrosal 
suture. 1: squamosal region of the ear. m: floccular fossa. n: wall of the temporal 
canal. o: aquaeduct vestibularis. q: crus commune. r: groove of the sulcus venus 
basilaris cranii. s: position of the semicircular canals. wu: internal auditory meatus. 


GEBEL ZELTEN, LIBYA III 


internal auditory meatus and after running along the aquaeduct falloppii leaves 
by way of the stylomastoid foramen. Postero-ventral to the fossa tensor tympani 
is a large opening—the fenestra rotunda, above which is the smaller fenestra ovalis 
(text fig. 5a). Posterior to and partly overhanging the fenestra ovalis is the stapedial 
promontory which provides origin for the stapedial muscle. The whole ventro- 
lateral face of the petrosal is very similar in Prolibytherium and Capreolus. 

The medial view of the petrosal (pl. 11, fig. 4) is dominated by the internal auditory 
meatus which has the shape shown (text fig. 5b). Cranial nerve VII enters the 
petrosal posteriorly and cranial nerve VIII enters anterior to this; separate openings 
for the nerves are visible inside the meatus. Above and slightly behind the meatus 
is the wide, shallow floccular fossa which houses the floccular lobe of the cerebellum. 
Between the floccular fossa and the internal auditory meatus the bone is swollen by 
the crus commune. The semi-circular canals lie ventral to the internal auditory 
meatus, these were located by X-raying the petrosal but owing to the size of the 
specimen this technique could not be used to discover any further details of the 
internal anatomy. 

The aquaeduct vestibularis and aquaeduct cochlea carry small veins. The medial 
region of the petrosal in Prolibytherium differs only slightly from that of Capreolus, 
the main difference being that the region around the floccular fossa and the fossa 
itself are more concave and larger in Capreolus. The petrosal of Okapia differs from 
Prolibytherium as the ventral part of the petrosal is expanded and the floccular 
fossa is relatively smaller in Okapia. 

Brain. Asingle endocranial cast of Prolibytherium was available (pl. 12, fig. I and 
2); this was formed from large calcite crystals and was dissected out of an almost 
complete cranium. The rhinal sulcus is situated very high on the lateral face of the 
brain (text fig. 6a) ; this reflects the greater importance of the rhinencephalon relative 
to the neopallium and is a primitive feature which is also found in Dremotherium, 
while in Capreolus and Okapia the rhinal sulcus is more ventrally situated. The 
anterior and posterior rhinal sulci meet each other at an angle of about 150°; this 
agrees with the angle given by Sigogneau (1968) for Dvemotherium. In both 
Prolibytherium and Dremotherium the two regions of the rhinal sulcus join with a 
smoother curve whereas in Capreolus the anterior and posterior regions bend sharply 
upwards before joining. The anterior rhinal sulcus runs slightly ventrally and its 
anterior end is lost, due to an imperfection of the cast. 

The olfactory lobes are produced anteriorly and a part of the olfactory peduncle 
is visible in dorsal view (text fig. 6b); this is similar to Amphitragulus and is more 
primitive than Dremotherium or Capreolus in which the olfactory peduncle is shorter 
and the lobes are flexed ventrally, lying under the neopallium. Posterior to the 
lateral fissure the brain is expanded laterally which results in a great widening of 
the posterior region; this is similar to Dremotherium but in Capreolus the posterior 
region is not expanded and in Okapia the brain is uniformly very wide. 

The cerebellum and vermis are relatively large and lie at the same level as the 
neopallium ; this is a primitive feature also found in Dremotheriwm. The neopallium 
is flattened in the vertical plane and its dorsal surface is almost flat as in Okapia 
whereas in Capreolus this region is curved antero-posteriorly and transversely. 


112 LOWER MIOCENE RUMINANTS 


The parts of the suprasylvian sulcus are clearly defined (text fig. 6a). The anterior 
branch curves medially with a very small descendant branch, whereas in Capreolus 
the inward curvature is more marked and a large descendant branch is produced 
running just in front of the sylvian sulcus. The central part of the suprasylvian 
sulcus is shallowly convex dorsally, this convexity is similar to Dremotherium but is 
less marked than in Capreolus. In Okapia (Clark 1939) the posterior and central 
parts of the suprasylvian sulcus are separated and overlap extensively. In Proliby- 
therium the posterior branch of the suprasylvian sulcus extends posteriorly almost 
as far as the cerebellum, it does not bifurcate whereas in Dremotherium a weak 
descendant branch is produced. A long posterior extension of the suprasylvian 
sulcus indicates an advance over the tragulid condition in which the posterior 


Fic. 6. The brain of Prolibytherium (B.M.26678) (Natural size x 0-7). (A) Right lateral 
view of the endocranial cast. (B) Dorsal view of the endocranial cast. a: posterior 
suprasylvian sulcus. b: lateral groove. c: anterior suprasylvian sulcus. d: sylvian 
sulcus. e: gamma sulcus. f: olfactory lobe g: anterior rhinal sulcus  h: anterior 
ectosylvian sulcus i:lateralfissure j: posterior rhinal sulcus and posterior ectosylvian 
sulcus k: piriform lobe 1: delta sulcus m: olfactory peduncle. 


GEBEL ZELTEN, LIBYA 113 


region of the sulcus is very short. The presence of a well marked descending limb 
of the suprasylvian sulcus, is stated by Black (1915) to be a giraffid feature and its 
absence in Prolibytherium is therefore a primitive feature. 

The ectosylvian and rhinal sulci are separate near the lateral fissure but fuse 
completely at a short distance from the fissure both anteriorly and posteriorly, as in 
Dremotherium. This feature is primitive and in Capreolus and Okapia the rhinal 
and ectosylvian sulci are separate over their whole length. The lateral fissure is 
triangular and large (text fig. 6a) as in Dremotheriwm and Capreolus. The sylvian 
sulcus is produced from the dorsal region of the lateral fissure, this sulcus runs 
antero-dorsally and almost reaches the suprasylvian sulcus (text fig. 6b) ; this feature 
is similar to the cervids rather than the giraffids Clark (1939). Behind the sylvian 
sulcus is a deep groove which is more nearly vertical in Capreolus but is absent in 
Dremotherium. In Dremotherium the sylvian sulcus is more vertical than in Capreolus 
or Prolibytherium. The posterior region, between the suprasylvian and ectosylvian 
sulci, is occupied by the ‘delta’ sulcus (Sigogneau 1968) ; this sulcus is forked anteriorly 
and curves ventrally in its posterior region. The ‘gamma’ sulcus is very deep and 
much shorter in Prolibytherium than in Dremotherium. 

The brain as a whole compares closely with that of Dremotherium but details of the 
sulci and olfactory lobes indicate that it was more primitive in Prolibytherium. 
The long sylvian sulcus is a cervid rather than a giraffid feature; however in 
Amphutragulus the sylvian sulcus is very short, this casts some doubt upon the 
importance of this feature in establishing relationships in early ruminants. As 
Prolibytherium is an early sivatheriid it is very unfortunate that no brain casts of 
sivatheriids were available. Agreement between the brain casts of Prolibytherium 
and the sivatheriids would probably be greater than the agreement between 
Prolibytherium and the giraffids. 

Mandible. The ascending ramus is high with a concave medial and a plane lateral 
face in the dorsal region. The mandibular foramen is at the same level as the tooth 
row, it is elongate antero-posteriorly and a shallow channel runs anteriorly from it. 
The lower part of the ascending ramus is concave laterally and provides insertion for 
the masseter muscle. The horizontal ramus is convex dorso-ventrally on both 
sides. The ventral edge of the ramus is curved with the deepest region below Mz 
(pl. 11, fig. 2). The bone surface slopes dorso-medially behind the Mg and a sharp 
ridge is formed which continues dorsally as the leading edge of the ascending ramus. 
A small posterior mental foramen lies ventral to Pe (pl. 11, fig. 2) in both specimens 
in which it is preserved. The anterior mental foramen is double in M.26680, it lies 
at the level of the posterior end of the symphysis and the two foramina communicate 
internally. The diastema of Prolibytherium is about the same length as the distance 
Pz to Mz, which is the same as in Capreolus but is much shorter than in Giraffa or 
Okapia in which the diastema is longer than the tooth row. 

Upper Dentition. The molars are generally similar in form; they are brachyodont 
with finely rugose enamel. M.z21gor isso heavily worn that the crown of M1 is almost 
completely worn away and the only remaining feature is the posterior fossette (pl. 9). 
The antero-labial corner of M2 bears a strong parastyle and both the paracone and 
parastyle have strong labial ribs. Posterior to the paracone the wear trace is very 


114 LOWER MIOCENE RUMINANTS 


wide but the mesostyle appears to have been originally part of the posterior lobe 
joining the paracone at a late stage in wear. The metacone is very stout and a slight 
postero-labial swelling indicates that a weak metastyle may have been present. 
The protocone is crescentic with the wear trace of its anterior region joining the 
parastyle and closing the fossette anteriorly (pl. 9). The posterior end of the pro- 
tocone joins the metaconule in the median valley. The metaconule is also crescentic 
and is posterior end joins the metacone or possibly the metastyle thus closing the 
posterior fossette. At the anterior end of the metaconule is a small crest which is 
produced into the median valley on the lingual side of the main region of fusion 
between the wear traces, this crest joins the protocone enclosing a small median 
enamel island in M! and M2 but this is not developed on M3 (pl. 9). Each molar has 
a strong entostyle in the median valley; in each case this is produced from the antero- 
lingual region of the metaconule but on M$ it joins a strong lingual cingulum pro- 
duced from the postero-lingual face of the protocone (pl. 9). Anterior cingula are 
present on each molar and posterior cingula were present on M! and M2. 

A single badly shattered molar showing very little wear is known (P.M.F.). The 
mesostyle has a strong labial rib which is joined to the metacone. The metacone has 
a weak labial swelling and the metastyle has a strong labial rib. The protocone and 
metaconule are angularly crescentic and the latter is smaller than the protocone. 
A strong accessory crest is present in the posterior fossette. 

The molars of Prolibytherium are smaller than those of Zavafa, detailed comparison 
is difficult owing to the heavily worn condition of the Prolibytherium dentition but the 
details of the median valley region differ between the two genera; this difference is 
due to the absence of the small conule in the anterior fossette of Prolibytherium 
resulting in a more simple wear pattern at the posterior end of the protocone. 

P4 is three rooted and brachyodont, it is smaller, relative to the molars and its 
lingual region is smaller than in Zarafa. The parastyle is strong with a large labial 
swelling and the paracone is very stout with lingual and labial ribs; the lingual rib 
is weaker than in Zarvafa but it has an anterior groove as in Zarafa and Palaeomeryx. 
Posterior to the paracone rib, the labial wall is almost flat as far as the metastyle. 
The metacone is stout and almost completely fused with the paracone, its labial 
swelling is weak though slightly stronger than that of Zarafa. The protocone is 
stout and joins the labial lobe at both ends thus closing the fossette. The fossette 
of P4is much deeper than that of Zarafa, this is also true of the fossettes of the molars 
indicating that the upper dentition of Prolibytherium is much higher than that of 
Zarafa, though still brachyodont relative to the advanced giraffids or sivatheriids. 
At the posterior end of the fossette of P4is a weak accessory crest (pl.g). The antero- 
lingual cingulum of the P4 is weak relative to that of Zarafa. 

P? is stout with a heavily worn crown which is concave antero-posteriorly. There 
are three strong ribs on the labial face which correspond to the parastyle, paracone 
and metacone. Between the parastyle and paracone ribs is a very deep groove 
(pl. 8) and a shallower groove separates the paracone and metacone ribs. No 
surface features are visible except a small, transversely elongate enamel island at the 
posterior end of the tooth. 

Lower Dentition. The lower dentition forms a closed series from Pg to Mg. The 


GEBEL ZELTEN, LIBYA 115 


enamel of the molars is finely rugose. P.M.B. has almost unworn molars and M.26681 
exhibits signs of only slight wear, these molars show that the cheek teeth are higher 
in Prolibytherium than in Zarafa. 

M3 has an accessory column but the anterior region differs only slightly from the 
other molars. The mesostylid has a strong lingual rib which runs postero-ventrally 
from the antero-lingual corner of the tooth (pl. 10, fig. 4). The metaconid is high and 
transversely compressed (pl. Io, fig. 3), its posterior end lies lingual to the anterior 
end of the entoconid which is lower than the metaconid and has a more diagonal 
orientation on the tooth (pl. to, fig. 3). The protoconid is crescentic and slightly 
angular, its anterior end joins the mesostylid early in wear. The posterior end of 
the protoconid joins the anterior end of the entoconid early in wear (pl. Io, fig. 3) 
and a little later the metaconid joins the entoconid thus isolating the hypoconid until 
very late in wear; plate 11, fig. 1 shows a heavily worn dentition in which the 
hypoconid of the Mg has just joined the protoconid. The hypoconid is lower than 
the protoconid, its anterior end stops in the median valley near the entoconid. 
The hypoconid is not crescentic in the unworn condition as the posterior region stops 
near the middle of the cuspid and in this region the cuspid falls away and is continued 
labially a few millimetres below the top of the crown; thus after moderate wear the 
cuspid becomes crescentic but the posterior region is always shorter and appears 
narrower even in the heavily worn condition. This feature is restricted to the 
Mg and is related to the presence of the accessory column. The accessory column is 
more simple in Prolibytheriwm than in Zarafa; it consists of a stout hypoconulid 
which is as high as the hypoconid and is similar in shape to the anterior half of that 
cuspid. The posterior half of the hypoconulid has a weak lingual twist but there is 
no approach to the crescentic shape found in the giraffids. The anterior half of the 
hypoconulid meets the postero-labial face of the entoconid and on the lingual side 
of this junction is a small fold of enamel which is probably a weak ectostylid. Mg 
has a feeble anterior cingulum and usually an ectostylid in the median valley. 

Mj and M¢ are similar to the anterior region of M3. At the postero-lingual corner 
of Mg is a small entostylid which joins the postero-lingual extension of the hypoconid ; 
in all specimens the entoconid is joined to the entostylid in this region. 

P, is long and narrow (pl. 11, fig. 1). The protoconid is the highest part of the 
tooth but the metaconid is almost as high, these two cuspids are joined by a narrow 
ridge which has a deep groove on its antero-lingual face (pl. 11, fig. 1). The anterior 
part of the tooth curves lingually and from the lingual face the lingual and antero- 
lingual paraconid and parastylid are produced; these branches are separated by a 
shallow lingual valley which is quickly lost during wear, leaving a single anterior 
region (pl. 11, fig. 1). Between the paraconid and metaconid is a deep, wide lingual 
valley at the lingual end of which is a strong stylid. The posterior region of P4 
consists of a stout labial hypoconid to which a postero-lingual entostylid and a lingual 
entoconid are joined. These two cuspids are separated by a shallow lingual valley 
which is lost early in wear but may persist for some time as a small enamel island. 
Between the protononid and the posterior region is a deep valley separating the 
metaconid and entoconid lingually and labially a deep groove separates the protoconid 
and hypoconid (pl. 11, fig. 1). A single unworn Py is known; on this the posterior 


116 LOWER MIOCENE RUMINANTS 


region is entirely separated from the anterior region as the lingual and labial valleys 
join over the crown of the tooth. The separation of these two regions is found in the 
giraffids and in some palaeomerycids. 

P3 has a high protoconid with a strong postero-lingual wing—the incipient meta- 
conid. The anterior region consists of a single wear trace derived from a paraconid 
and parastylid asin Py. A lingual stylid closes the anterior valley but this is much 
weaker thanin Py. The posterior region is separated from the protoconid by a strong 
lingual valley and a weaker labial valley. The hypoconid is feeble in P3. The 
entoconid is strong but the entostylid is very slender and forms the posterior face of 
the tooth. 

The Pz of Prolibytherium is a high conical tooth (pl. 11, fig. 2) of the primitive 
ruminant premolar form. The protoconid is high and a weak postero-lingual 
fold represents the metaconid. Anteriorly the paraconid consists of an unbranched 
crest which runs anteriorly from the face of the protoconid (pl. 11, fig. 1) and twists 
lingually at the distal end. The posterior region is transversely wide with a weak 
entoconid and entostylid. This tooth is similar that of Palaeotragus roueni but in 
this species the anterior crest is divided into a parastylid and a paraconid which is a 
more advanced condition. 

The Skull as a Whole. The dorsal view of the skull is dominated by the enormous 
ossicones which are completely fused to the frontal and parietal bones. The great 
thickening of the basioccipital region and the occipital condyles is directly related to 
the presence of the ossicones. Though the facial region is poorly known it is of great 
interest as a lacrymal fossa and paired lacrymal foramina are present, these are 
primitive features previously unrecorded in the Giraffoidea but similar to the cervoid 
or dremotherioid condition. The maxilla is shallow as in Capreolus and it is likely 
that the basicranial and basifacial regions were widely divergent as in Zavafa. The 
endocranial cast shows similarities to the dremotherioids. In most features the skull 
of Prolibytheriwm is similar to the early pecorans but this resemblance is decreased by 
the presence of the ossicones in Prolibytherium. 


TABLE 8 


Prolibytherium magniert. Measurements of the skull and dentition 


The Skull 
B.M.21901 
Postorbital length. (From anterior edge 
of orbit to occipital condyle) : 132 mm 
Width of ossicones above the orbit 320 mm 
Maximum length of the ossicones 425 mm 
Width of condyles 51 mm 
Height of occipital region 71 mm 
Height of occipital region plus ossicones 114 mm 
Maximum width of occipital region 93 mm 
The Upper Dentition 
B.M.21901 
Length Width 


p2 12-5 mm 9:0 mm 


aie oe eee 


GEBEL ZELTEN, LIBYA 117 
TABLE 8 (cont.) 
p4 II1-o mm I4°;0 mm 
M} 15:0 mm 17°55 mm 
M2 18-0 mm 20:0 mm 
M3 20:0 mm 20:0 mm 
The Lower Dentition 

M.21899 M.26681 B.U.20175 P.M. A. P.M. B. P.M. C P.M. D. 
P2 
Width 5°3 mm as -— — — + — 
Length 10-0 mm — — — — -- — 
Ps 
Width 6-5 mm = — 7-0 mm — as — 
Length 11-0 mm — Izomm 12:0mm --- — — 
Pa, 
Width 8-5 mm — 9-0 mm 775 mm a 7°5 mm — 
Length 130 mm — 145mm 12°8mm — 13-5 mm — 
Mi 
Width 12.0 mm — Iz0mm 12;°0mm — — 11-5 mm 
Length 1370 mm — I5omm 135mm 140mm — 16°5 mm 
Me 
Width 12°5 mm — I3z0mm 13°0mm — — 130 mm 
Length 16°5 mm — — 185mm 185 mm — 17-5 mm 
M3 
Width izomm 130mm 13:°mm 12°55 mm — 130 mm 
Length 235mm 265mm 265mm 24:°5mm 25:0mm — 25-0 mm 


Post-cranial material. Details of the skull indicate that Prolibytherium was 
probably similar to the more primitive cervids and it is therefore likely that its 
post-cranial material resembled that of the cervids. On this basis the post-cranial 
material of Prolibytheriwm was identified by comparison with a skeleton of Capreolus. 


MATERIAL 
B.U.20153 A proximal fragment of a left scapula. 
B.U.20154a The distal end of a left humerus. 

b A complete left radius. 

c The proximal end of a left ulna. 
B.U.20155 The distal end of a metacarpal. 
B.U.20156 _ A first phalange. 

B.U.20157__—CA first phalange. 

B.U.20158 __ A first phalange; posterior? 
B.U.20159 The proximal end of a right tibia. 
B.U.20160 The proximal end of a left tibia. 
B.U.20161 =‘ The distal end of a right tibia. 
B.U.20162 The distal end of a left tibia. 
B.U.20164 =A right calcaneum. 

B.U.20165_ ~—A right astragalus. 

B.U.20166 __—A right astragalus. 
B.U.20167__—A left astragalus. 

B.U.20168 A right astragalus. 


118 LOWER MIOCENE RUMINANTS 


B.U.20169 A distal, metatarsal fragment. 

B.U.20170 An almost complete atlas vertebra. 
B.U.20171 _ A slightly broken seventh cervical vertebra. 
B.U.20172 A complete first thoracic vertebra. 
B.U.20173, An almost complete thoracic vertebra. 


Scapula. The glenoid region of the scapula has an almost circular outline with a 
small glenoid notch (text fig. 7a). The coracoid process is strong but the tuber 
scapulae is weak. The spine begins near the glenoid and rises steeply indicating the 
presence of a strong acromion process. The neck of the scapula is wider than in 
Zarafa or Okapia; it has a deep vascular groove on the medial surface and a strong 
tuberosity on the posterior edge which is the area of origin for the teres minor muscle. 
The outlines of the glenoids in four giraffoid genera (text fig. 7) demonstrate the dif- 
ferences which exist in the development of the coracoid process and the tuber 
scapulae. The tuber scapulae of Prolibytherium (text fig. 7a) is very feeble, in Zarafa 
it is stronger (text fig. 7c) and in the extant giraffids it is very strong (text fig. 7b and 
d). The coracoid process is strongly developed in Prolibytherium and weakly 
developed in the giraffids indicating that in Prolibytheriwm the coraco-brachialis 
muscle was more highly developed than in the giraffids. The neck of the scapula 
indicates that the bone was shorter and wider than that of Okapia and probably 
resembled the scapula of Ovis. 

Humerus. The coronoid fossa is much deeper than in Okapia or Giraffa; this 
fossa provides origin for the extensor carpi radialis and the common digital extensor 
muscles, both of which were strongly developed in Prolibytherium. The lateral 
condyle is narrow with a transversely concave face, this concavity is caused by very 
strong lateral and intermediate ridges. The intermediate ridge separates the 


Fic. 7. The glenoid cavity and surrounding region of the left scapula. (a) Prolibytherium 
(B.U.20153) Natural size. (B) Okapia 0-5 x Natural size. (c) Zarafa (B.U.20123) 
0:5 x Natural size. (p) Givaffa, 0-25 x Naturalsize. a: glenoid cavity. b: glenoid 
notch. c:coracoid process. d: tuber scapulae. 


GEBEL ZELTEN, LIBYA 119g 


condyle from the synovial fossa and all the ridges of the distal head of the humerus are 
much stronger than in Okapia. The olecranon fossa is very deep and the articular 
region extends further into the fossa than in Okapia. The medial epicondyle is very 
strong, it is produced distally as a large process overhanging the medial condyle 
(text fig. 8a). The medial condyle of Okapia is more weakly developed than that of 
Prolibytherium and slopes proximally from the condyle (text fig. 8b). The medial, 
distal and lateral faces of this epicondyle are very heavily sculptured in Prolibytherium 
and the main digital flexor muscles have areas of origin on this epicondyle. The 
lateral epicondyle of Prolibytherium is slightly stronger than that of Okapia, this 
region provides origin for the ulnaris lateralis muscle. 

Radius. The central part of the proximal face of the radius is deeply excavated 
posteriorly for the insertion of the interosseous ligament. This excavation is about 
the same size in Prolibytherium and Okapia (text fig. 9). The postero-proximal 
region of the bone is sculptured for attachment to the ulna and this region bears two 
wide concave facets which are continuous with the proximal facets and articulate 
with the ulna. The lateral part of the proximal region forms a strong lateral 
tuberosity providing insertion for the lateral ligament of the elbow and also origin 
for the common lateral digital extensor muscles. The radial tuberosity, about the 
same size in Prolibytherium and Okapia, provides insertion for the biceps brachii 
muscle. In Prolibytherium it is situated at some distance distal to the articulation 
in contrast to Okapia in which the tuberosity is very near the articulation (text 
fig. 9). 

The shaft of the radius is slender and curved anteriorly as in Okapia and Capreolus. 
The distal end is transversely narrower than in Okapza; it has the usual articulations 


Fic. 8. Medial view of the distal end of the humerus. (a) Prolibytherium (B.U.20154a). 
Natural size. (B) Okapiao-5 x Naturalsize. a:medialepicondyle. b: medial condyle. 
c: shaft of humerus. 


120 LOWER MIOCENE RUMINANTS 


forthe carpals. The area lateral to the cuneiform facet is sculptured indicating a very 
close attachment of the ulna in this region. In Prolibytherium the posterior face of 
the radius is convex in the region immediately proximal to the distal facet; this 
contrasts with Okapia in which this face is concave. The lateral tuberosity of the 
distal end is strong and the medial tuberosity is stronger in Prolibytherium than in 
Okapia; these tuberosities provide insertion for the ligaments of the carpal joint. 

Ulna. The olecranon process is flattened and though it is broken off distally it was 
probably aslong as that of Okapia. Theshaft of the ulna is also flattened transversely 
and bends medially at its distal end asin Okapia. The interosseous space is short and 
relatively narrow. In Prolibytherium the articular facet is convex transversely, in 
contrast to Okapia in which the facet is flat transversely. The greater convexity 
of the facet reflects the deeper synovial fossa and stronger ridges of the distal end of 
the humerus. The facet of the olecranon in Prolibytherium extends further dorsally 
than in Okapia resulting in a more elongate facet and at full extension the olecranon 
fits into the deep olecranon fossa and locks the elbow. 

Metacarpal. The distal end of the metacarpal has a large nutrient foramen in the 
mid-line proximal to the condyles asin Zarafa. The distalend of the boneis wideand 
indicates that the metacarpal was relatively stout. The condyles are of the usual 
ruminant pattern with strong keels as in the cervids. 

Tibia. In Prolibytherium the proximal head of the tibia is narrower than that of 
Okapia but is otherwise similar in general anatomy. The cnemial crest is higher in 
Prolibytherium than in Okapia or Zarafa (text fig. 10) resembling that of Capreolus. 
The medial face of the cnemial crest is plane and the anterior region of the crest is 


Fic. 9. The radius of Prolibytherium. (A) The anterior face of the proximal region of the 
radius in Prolibytherium (B.U.20154b). Natural size. (B) The anterior face of the proximal 
region of the radius in Okapia. 0-5 x Natural size. (c) The proximal articular facet of 
the left radius in Pyolibytherium. Natural size. (p) The proximal articular facet of the 
left radius in Okapia. 0:5 x Natural size. 


GEBEL ZELTEN, LIBYA 121 


heavily sculptured. The anterior tuberosity of the crest is wide and similar to that 
of Capreolus. The lateral face of the crest forms a deep elongate concavity which is 
deeper than that of Okapia or Capreolus. 

The distal end of the tibia is narrow transversely. The medial articular groove is 
very deep and the intermediate ridge is high resembling that of Zarafa or the cervids. 
The anterior edge of this ridge continues as a high anterior process. The synovial 
fossa is large and extends laterally and medially into the articular grooves. The 
articulation for the lateral malleolus consists of a wide posterior facet and a smaller 
anterior facet asin Zarafa. The anterior and posterior facets are separated by a deep 
groove for the tendons of the lateral extensor muscles of the foot. The medial 
malleolus is heavily sculptured and as strong as in Okapia. 

Calcaneum. The calcaneum differs in minor details from that of Palaeomeryx but 
in major features it is more similar to Palaeomeryx than to any other giraffoid. 

Astragalus. In agreement with the calcaneum the astragalus of Prolibytherium 


Fic. 10. The proximal head of the right tibia. (a) Prolibytherium. (B.U.20159 and 
B.U.20160). Natural size. (B) Okapia 0-5 x Natural size. (c) Zavafa (B.U.20146) 
0-5 x Naturalsize. (D) Capreolus Natural size. a:medialcondyle. b: lateral condyle. 
c: tibial spine. d: cnemial crest. 


122 LOWER MIOCENE RUMINANTS 


resembles that of Palaeomeryx in all its main features. Both the astragalus and 
calcaneum contrast strongly with those of Okapia but this is mainly due to the 
specialized nature of the ankle in Okapia. 

Metatarsal. This bone is larger than the metacarpal; the reverse of the condition 
in Okapia and Giraffa but similar to the cervid condition. The distal end is more 
flattened antero-ventrally than in Okapia or Zarafa. The anterior face of the bone 
carries a deep channel which is open and passes between the condyles, this channel 
is very restricted in the region just proximal to the condyles and the walls of the 
channel are sculptured as in Zavafa. The condyles are similar to the cervids or 
Zarafa. 

Phalanges. The phalanges identified as Prolibytherium are smaller than those of 
Zarafa but are otherwise similar in all details and reference should be made to the 
description of Zarafa (p. 97). 


THE VERTEBRAL COLUMN 

Allas. The atlas of Prolibytherium (text fig. 11c and d) is identified by its size 
which agrees with the size of the occipital condyles. The general form of the atlas 
is similar to that of other ruminants. The anterior articular facets are very deep and 
their lateral curvature is sharper than in Okapza, agreeing with the condition of the 
occipital condyles. The wing of the atlas is broken off. The intervertebral and 
alar foramina are closely associated ventrally and dorsally they have a common 
opening (text fig. IIc) as in Capreolus but in contrast to Okapia where they are widely 
separated. The ventral face of the atlas is similar to that of Okapia and the ventral 
tubercle is very strong (text fig. 11d). The posterior articular facets are swollen 
medially and concave laterally, differing from Okapza in which the facets are more 
nearly plane. In Prolibytherium the posterior articular facet extends further laterally 
than that of Okapia and as in Giraffa, it is continued onto the postero-lateral process 
of the wing. Although this process is broken off it appears to have been as strong as 
that of Givaffa, indicating a strengthening of the atlanto-axis articulation in 
Prolibytherium. The bone of the atlas is very thick. 

Cervical vertebrae. The centrum of the seventh cervical vertebra (text fig. I1a) 
is stouter than that of Okapiza and has a strong ventral ridge. The anterior end of 
the centrum is displaced dorsally relative to the posterior end but less so than in 
Okapia. On the posterior face the lateral facet for the head of the rib is wider and 
more clearly defined than in Okapfia. The posterior articular process is lateral only 
and the articular facet is more elongate in Prolibytherium than in Okapia (text fig. 
I1a). The anterior articular process is similar to that of Okapza with similarly shaped 
facets. The transverse processes and neural spine are broken off. 

Thoracic vertebrae. The centrum of the first thoracic vertebra is very short and 
stout. The anterior facet of the centrum (text fig. 11g) is shallowly convex and the 
facets for the head of the rib (text fig. 11f) face much more anteriorly than in Okapza. 
The posterior facet of the centrum is shallowly concave with wide lateral facets for the 
heads of the ribs (text fig. 11e). The ventral face of the centrum is not greatly 
swollen. A small tubercle is produced at the anterior end of the ventral face and 
the paired posterior tubercles are very laterally situated. The transverse process is 


GEBEL ZELTEN, LIBYA 123 


strong and the saddle shaped articulation for the tubercle faces ventrally (text fig. 
11f) whereas in Okapia it faces antero-ventrally. The anterior articular process is 
similar to that of Okapia, with wide lateral articulations extending further medially 
thanin Okapia. The articulation of the posterior process is median in Prolibytherium 
and the paired facets are well defined (text fig. 11e); they are elongate, narrow and 
opposed at an acute angle as in Givaffa. The neural spine slopes more posteriorly 
than in Okapia, it is the same relative length in Prolibytheriwm and Okapia. The 


Fic. 11. The vertebrae of Prolibytherium. (a and B) Lateral and posterior views of the 
seventh cervical vertebra. (B.U.20171). (c and D) Lateral and posterior views of the 
atlas (B.U.20170). (£, F and G) Posterior, lateral and anterior views of the first thoracic 
vertebra. (B.U.20172). All 0-5 x Natural size. Fine stippling indicates articular 
regions. a: neural spine. e: common dorsal opening of the intervertebral and alar 
foramina. g: transverse process. h: anterior articular process. k: tubercular facet. 
1: posterior facet for the head of the rib. m: posterior articular facet. n: anterior face 
of centrum. o: posterior face of centrum. p: ventral tubercle. 


124 LOWER MIOCENE RUMINANTS 


cross-section of the neural spine is triangular with thickening of the posterior edge 
and heavy sculpturing in the region just dorsal to the posterior articular process. 

A single vertebra is known from the posterior thoracic region of Prolibytheriwm, 
this is probably the tenth or eleventh thoracic vertebra. The neural spine is stronger 
than in Okapia and it slopes more steeply posteriorly. Both faces of the centrum 
and the anterior and posterior articular processes of Prolibytherium are similar to those 
of Giraffa. 

Functional interpretations. Features of the fore-limb bones of Prolibytherium 
indicate that the locomotory muscles were very strong and a requirement for strength 
rather than speed is indicated. The animal had relatively short limbs probably not 
unlike those of Ovis. The presence of large ossicones would have necessitated great 
strength in the forelimbs and if the ossicones were used in intraspecific combat, as 
seems likely, then this requirement for strength would be exaggerated. 

Details of the skull and atlas vertebra indicate that great forces were encountered 
by the head of Prolibytherium. The lower cervical region is represented by the seventh 
cervical and first thoracic vertebrae. If the neural spine of the seventh cervical 
vertebra was vertical during life, then the neck extended almost horizontally from 
the shoulders and it is likely that the head did not rise much above the level of the 
shoulders. The stoutness of the centra of the lower neck vertebrae and the shortness 
of the atlas indicate that the neck was short and probably very stout. 


TABLE 9 
Measurements of Prolibytherium magnieri, post-cranial material 
Vertebrae 
B.U.2z0170 B.U.zo17r B:U.201%72” “B:U-zor7z3 
Length of centrum 28 mm 30 mm 23 mm 27 mm 
Total height of vertebra 34 mm — 102 mm — 
Depth of centrum — 19 mm 18 mm 16 mm 
Width of anterior end of centrum = I5 mm I9 mm 22 mm 
Width of posterior end of centrum — 27 mm 29 mm 30 mm 
Scapula 
B.U.20153 
Width of neck of scapula (Minimum) 25 mm 
Depth of neck of scapula (Minimum) 14mm 
Width of glenoid (Anterior-Posterior) 30 mm 
Depth of glenoid (Transverse) 25 mm 
Humerus 
B.U.20154a 
Distal end 
Width across epicondyles 35 mm 
Antero-posterior depth of distal 
articular surface 18 mm 
Radius 
B.U.20154b 


Width of proximal articular surface 35 mm 


GEBEL ZELTEN, LIBYA 125 


TABLE 9g (cont.) 


Depth of proximal articular surface: 


Minimum 13 mm 
Maximum 18 mm 
Total length of bone 210 mm 
Width of distal articular surface 29 mm 
Depth of distal articular surface 21 mm 
Metacarpal 
B.U.20155 
Width of distal end 27 mm 
Depth of distal end 15 mm 
Phalanges 
B.U.20156 3B.U.20157 B.U.20158 
Length 37 mm 37 mm 33 mm 
Width of proximal end 13 mm I4 mm 13 mm 
Depth of proximal end I4 mm 14 mm I4 mm 
Width of distal end II mm II mm Io mm 
Depth of distal end og mm og mm og mm 
Tibia 
B.U.20159 B.U.2z0160 B.U.20161 B.U.20162 B.U.20163 
Width of proximal end 47 mm 46 mm a — — 
Depth of proximal end 46 mm 44 mm — — — 
Width of distal end — — 29 mm 27 mm 30 mm 
Depth of distal end — — 21 mm 21 mm 23 mm 
Calcaneum 
B.U.20164 
Total length 70 mm 
Length of tuber calcis 48 mm 
Width across sustentaculum I9 mm 
Depth of tuber calcis 18 mm 
Maximum depth of bone 28 mm 
Astragalus 
B.U.20165 3B.U.20166 B.U.20167 B.U.20168 
Maximum length 32 mm 36 mm 33 mm 33 mm 
Minimum length 26 mm 30 mm 26 mm 25 mm 
Width proximally 20 mm 20 mm 20 mm 18 mm 
Width distally 18 mm 20 mm 19 mm 18 mm 
Maximum depth 15 mm 16 mm 16 mm I5 mm 


Family BOVIDAE Gray 1821. 
Subfamily BOVINAE Gill 1872. 
Diacnosis: This subfamily is defined by Pilgrim (1939 p. 249). 


Tribe BOSELAPHINI Simpson 1945. 
DiacGnosis: This tribe is defined by Gentry (1970 p. 245). 


126 LOWER MIOCENE RUMINANTS 


Genus PROTRAGOCERUS Depéret 1887 


TYPE SPECIES: Protragocerus chantret Depéret 1887. 


MATERIAL: 
M.26687 An isolated right horn core fragment. 
B.U.20113 Anisolated left horn core fragment with part of the frontal attached. 
B.U.20114 An isolated right horn core fragment. 


DEscriPTiIon: M.26687 (pl. 13, fig. 1) is the best preserved of the three specimens; 
part of the orbital region is preserved in the ventro-lateral region of the specimen 
and in the medial part of the orbital roof a small supraorbital foramen runs dorso- 
medially for a short distance in the bone, before turning anteriorly to emerge in the 
antero-medial region of the horn core, as in Protragocerus gluten. The lateral region 
of the orbit extends slightly more laterally than the lateral face of the pedicle, 
which results in a weak lateral swelling in this region; however the horn core is more 
laterally situated than in Protragocerus gluten which may indicate that the Gebel 
Zelten species is more primitive. The region of the frontals lying between the bases 
of the horn cores, is slightly higher than the edge of the orbit and in B.U.20113 
the area immediately medial to the horn core base is concave as far as the median 
suture, which is strong and slightly raised. 

The horn core is set diagonally on the skull roof and in B.U.20113 it slopes laterally 
at an angle of about 20° from the vertical; however in M.26687 this angle is smaller. 
The horn core also slopes posteriorly at an angle of 35° in all three specimens; which 
is very similar to the posterior slope in Protragocerus gluten (Pilgrim 1937). The 
surface of the horn core carries many pronounced vertical ridges and grooves which 
terminate a short distance above the skull roof, there are no cross striations. 

The anterior and posterior keels are strong but do not show any signs of the torsion 
exhibited by more advanced forms. There is no medial keel but the medial face of 
the horn core is convex antero-posteriorly and a slight swelling may be detected near 
the middle of the face, this could be an incipient third keel. The medial face is 
concave proximo-distally, which indicates that the horn cores, though divergent at 
their bases, may have become more convergent distally. The lateral face is convex 
proximo-distally at the base but shows slight concavity distally. The cross-section 
of the horn core agrees closely with that of Protragocerus gluten (Pilgrim 1937) and 
the agreement with Protragocerus chantret (Thenius 1956) is more distant. On the 
basis of this evidence the horn cores from Gebel Zelten, although more primitive 
than other specimens of Protragocerus, do exhibit features which indicate their 
close relationship and also incipient features which could lead to the characteristics 
exhibited by the more advanced species of the genus. 

In B.U.20113 sufficient of the roof is preserved for an estimate of the width across 
the orbits to be made, this was certainly not greater than 6-5 cm and not less than 
6-0 cm which is much smaller than Protragocerus gluten and indicates an animal in 
the same size range as the small mandible which has been identified as Gazella sp. 
The features of the horns and mandible which separate them into different sub- 
families are very conclusive and the chances that these two specimens could be from 
the same species are very small indeed. 


GEBEL ZELTEN, LIBYA 127 


Genus EOTRAGUS Pilgrim 1939 


Dracnosis: The genus Eotragus is defined by Pilgrim (1939 p. 137). 
TYPE SPECIES: Eotragus haplodon (von Meyer) 1846. 


Eotragus sp. 


MATERIAL: 
M.26688 A single isolated hor core. 
M.26689 A single isolated horn core. 


DESCRIPTION: The supraorbital foramen penetrates the roof of the orbit and the 
canal curves inside the bone, to open on the anterior face of the horn core base near 
the centre of the base. The horns were almost vertical and perhaps slightly con- 
vergent ; they were situated supraorbitally and were very near the edge of the orbit. 
The surface of the horn core is excavated by a large number of proximo-distal 
grooves but transverse grooves are totally absent (pl. 13, fig. 1). A strong keel is 
present on the posterior face of the horn core; this keel is stronger in M.26689 than 
it is in M.26688 but as the latter is from an older individual the strength of the keel 
may have decreased with age. The cross-section of the horn core agrees closely with 
that of Eotragus sansamensis (Thenius 1952 fig. 5). The lateral face is convex 
proximo-distally agreeing with Eotragus haplodon (Thenius 1952) and the Gebel 
Zelten specimens also agree in size with this species ; however the horns were certainly 
longer in the Gebel Zelten species than in E. haplodon as the opposing faces converge 
more gradually in the former species. 


TABLE IO 
Horn cores 


Protvagocerus Eotragus 
B.M.26687. B.U.20113 B.M.26688 3B.M.26689 
Maximum antero-posterior 


thickness of horn core 27°38 mm — 20-6 mm 16-9 mm 
Maximum antero-posterior 
thickness of pedicle 25°5 mm 25°7 mm 19'4 mm 16-7 mm 
Maximum transverse width 
of horn core 18-0 mm — I77I mm 14-3 mm 
Maximum transverse width of pedicle 17-7 mm — 1770 mm 15°55 mm 


Subfamily ANTILOPINAE Baird 1857 


Diacnosis: The subfamily was defined under the name Gazellinae by Pilgrim 
(1939 P. 30). 


Genus GAZELLA De Blainville 1816 
Diacnosis: The genus was defined by Gentry (1970 p. 292). 


128 LOWER MIOCENE RUMINANTS 


Gazella sp. 


REMARKS: Species of Gazella are identified as much on the basis of the horn cores 
and occipital region as by the dentition. The confused state of classification within 
the genus is being gradually resolved (Gentry 1964, 1966, 1970) but at the moment 
the material from Gebel Zelten is insufficient to identify the specimen with any existing 
species or to allow the establishment of a new species. 


MATERIAL: 
M.26685 An isolated left mandible, dentition showing medium wear. 
M.26686 A left mandibular fragment, Ms partially erupted. 


Mandible. The mandible is clearly bovid and the dentition confirms this. For 
purposes of comparison mandibles of Gazella capricornis and G. pilgrimi were used: 
with reference to the former Gentry (1970) states: 

‘Gazella capricornis (Wagner) is the gazelle of the famous Pikermi lower Pliocene 
fauna from Attica. ... Its teeth frequently show primitive characters: 
basal pillars on other teeth than the upper and lower first molars, strong ribs 
between parastyle and mesostyle of upper molars, medial wall of lower molars 
not very flattened, fairly shallow mandibular horizontal rami, and probably a 
longer premolar row.’ 

The species G. pilgrimi; with which Gentry synonymized G. gaudryi; is a more 
advanced form from Samos in which the dentition lacks primitive characters. 

In the Gebel Zelten species the mandible is deep with the deepest point lying 
below the anterior end of Mg. The lateral face of the mandible is convex with a 
strong swelling in the posterior region as in Syluicapra. A small posterior mental 
foramen lies below the anterior end of Pg. The anterior mental foramen is very large 
and double as in Sylvicapra. The diastema is short and though the anterior region 
is missing its length was probably similar to that of Gazella or Sylvicapra. The 
medial face of the mandible (pl. 13, fig. 8) is convex dorsally but a shallow concavity 
runs antero-posteriorly along the ventral part of this face. The mandibular foramen 
is large and below it is a shallow mandibular groove as in Gazella. 

Lower dentition. The molars of the Gebel Zelten species are more brachyodont 
than in G. capricornis or G. pilgrimi and cingula are lacking in all three species. On 
Ms the mesostylid is as strong as that of G. capricornis but is weaker than in G. 
pilgrimi. The metaconid is high, transversely flattened and set diagonally on the 
tooth causing the metastylid to be produced lingually. In G. capricornis the lingual 
cuspids are parallel to the axis of the tooth. The metaconid has a weak lingual 
swelling. The metastylidis very weak andislost after medium wear. The entoconid 
is as high as the metaconid and has a more feeble lingual swelling, it is set more 
nearly parallel to the axis of the tooth than the metaconid. The protoconid is high 
and crescentic with no trace of a ‘Palacomeryx fold’, its anterior region joins the 
mesostylid very early in wear. The posterior end of the protoconid meets the 
metaconid and entoconid at the lingual end of the median valley. The hypoconid 
is lower than the protoconid but is less isolated than in the palaeomerycids. The 
posterior end of the hypoconid joins the entoconid, isolating the hypoconulid which 
forms the accessory column; this is lower than the hypoconid and is crescentic, 


GEBEL ZELTEN, LIBYA 129 


resembling closely the accessory column of G. capricornis or G. pilgrimu. Excluding 
the differences mentioned the Mg of the Gebel Zelten species is very similar to the 
two European species. 

Mg resembles the anterior region of Mg. The mesostylid is stronger in Mz than 
in Mg (pl. 13, fig. 2), this may be a compensatory strengthening as the metaconid is 
more nearly parallel to the axis of the tooth in Mg. Mj is more worn but otherwise 
similar to Mg. Each molar has a strong ectostylid and M3 has a weak stylid in the 
posterior valley, these stylids are similarly developed in G. capricornis. 

The Py, of the Gebel Zelten species is short with a high protoconid which gives off 
a strong postero-lingual metaconid. The anterior region consists of a paraconid 
which is stout and directed antero-lingually. A parastyle does not appear to have 
been developed as the lingual face of the paraconid does not bear a groove (pl. 13, 
fig. 2). The posterior region is wide and the hypoconid is stout with a strong labial 
swelling (pl. 13, fig. 2) which is separated from the protocone by a deep labial groove. 
The entoconid is strong and wide but it is heavily worn and the presence of an 
entostylid cannot be established; the absence of a lingual groove on the face of the 
entoconid(pl. 13, fig. 3) indicates that an entostylid was probably not present. 

The Py, of G. capricornis is similar to that of the Gebel Zelten species. The 
hypoconid is strong in G. capricornis and has a strong labial swelling as in Gazella sp.. 
The metaconid, entoconid and entostylid are similar in the two species but the 
anterior regions differ as the paraconid and parastylid are widely separated in 
G. capricornis but are joined in Gazella sp.. The Py of G. pilgrimt is smaller than in 
Gazella sp. and the hypoconid is more feebly developed. The entoconid and ento- 
stylid are more widely separated in G. pilgrimi than in Gazella sp. and, as in G. 
capricornis, the paraconid and parastylid are also widely separated in G. pilgrimt. 

The P3 is much shorter than the Py, (table 11); the lingual region is badly broken 
(pl. 13, fig. 3). The labial wall has a strong hypoconid swelling asin Py. The Ps of 
G. capricornis is highly developed and is as long as the Py (table 11); its paraconid 
and parastylid are strongly separated as on the Py, and in contrast to the Pg of 
Gazella sp. in which the anterior region is not divided. The Ps of G. pilgrimt is 
smaller than that of Gazella sp. but the paraconid and parastylid are separated as in 
G. capricornis. The Pe is missing in M.26685 but it appears to have been greatly 
reduced in length and was probably comparable to the Pe of G. pilgrim: or G. 
capricorms. 

The molars of the Gebel Zelten gazelle are therefore similar to those of the European 
Pliocene species and they were similar in length and width to those of G. capricornis; 
however in that species the molars are more hypsodont than in Gazella sp. and even 
after medium wear the molars of G. capricornis are almost as high as the unworn 
dentition of M.26686. The molars of G. capricornis are more advanced than those 
of the Gebel Zelten gazelle. The premolar row is relatively long in G. capricornis 
and short in Gazella sp. and G. pilgrimi ; thus in this respect Gazella sp. resembles the 
more advanced G. pilgrimi. It is not possible to place the Gebel Zelten gazelle with 
either of these species as it shows features which are present in both species and also 
exhibits some features such as degree of brachyodonty and details of the premolars, 
which are more primitive than in either species. 


LOWER MIOCENE RUMINANTS 


130 


UII 9-6 
wu 1-6 
WU 0-8 
wut 2.2 
wut ¢.Z 


%9-oL 
wut o-.VE 


wut 2.1 

WIW 9-01 

UWI 0-01 
wut ¥z 


WU 9-9 
wut 4.9 
wut 9-S 


uu L-6 
wut S.6 


wu +. 
WU Z-S 
wut Z.€ UWIU Z-S 
UIPIM. qysue'] 
vIokI WE 
SWUAOIUAGDI *5) 


%Wri-SS 
UIU 1-Z€ 


wu S-V1 

WIW 0.9 UIUI O-O1 

uur o.S Ulu 1-6 
wut 2.21 


wut L.9 


wurut €.2 
wut Z.¢ 
wut Z.z wut Z.¢ 
UIPIM qysueT 
LLib we 
wurasyrd “5 


wu S.F 
uur L.€ 


UIUI 9-9 wut 0.S1 


UIPIM. yysueT 
93997 Wa 
“ds vIaz05) 


Il alavy 


Wu 0-6 
wut £-g 
wut o.Z 
UIUL 8-9 
uu 6.¢ 


%r-gS 
wu F-r€ 


wiul 9-F1 

UIUI O-IT 

uw S.6 
UU OZ 


WU 9-9 
wut o.Z 
wut 2.9 


wut $.¢ WIUI 9-g 
wut o-F uur z-Z 
— wut 0. 
UIPIM yysue'T 
Sgo9z' Wd 
“ds vazvy) 


UMOIO 
jo doz 0} Yoou woz 
7YsIoy UNUWIIxe[, 
(ooI—y}8U9] IeOJA)) 
sus] Iejpoy 
0} IejoulsIg % 
MOI Ie[OUL 
JO Y}SUg] [eJOL, 


MOL Teyouroid 
JO Y}Sug] [CIOL 


GEBEL ZELTEN, LIBYA 131 


The presence in the Zelten fauna of three species of bovids in the early Burdigalian 
is surprising as, with the exception of European sites and the Hsanda Gol of Asia, 
bovids are of later occurrence. The presence of three bovid genera representing the 
two most important subfamilies of the Bovidae indicates that the bovids were already 
well established in the early Miocene and therefore they must have diverged from their 
ancestral stock at some time during the Oligocene. The presence of bovids at Hsanda 
Gol is not yet well established though Trofimov (1968) figures very bovid like lower 
molars of Palaeohypsodontus and this may indicate that the ancestry of the bovids 
must be sought in the Oligocene of Asia. 


Ill. THE EVOLUTION OF PRIMITIVE GIRAFFOIDS 


The Giraffoidea was established by Simpson (1931) to include the Palaeomerycidae 
and Giraffidae ; Simpson (1945) demoted the Palaeomerycidae to subfamily level and 
transferred it to the Cervoidea, leaving the Giraffoidea containing the Giraffidae and 
the Lagomerycidae. 

The Palaeomerycidae was established by Lydekker (1883) taking its name from 
Palaeomeryx von Meyer 1834. Lagomeryx Roger 1904, was established to include 
small species of Palaeomeryx, bearing branching ossicones. This situation persisted 
until Roman and Viret (1934) suggested that the two genera were synonymous; 
this suggestion was supported by Teilhard de Chardin (1939). De Chardin also 
suggested that a separate family should be created to accommodate Lagomeryx, 
Procervulus and ‘other so called cervids’. This was left to Pilgrim (1941) who 
proposed the name Lagomerycidae for a family including the two genera named by 
de Chardin and Climacoceras which had been placed in the Cervidae (MacInnes 1936). 

Stirton (1944) discusses the relationships of the palaeomerycids and states that 
Lagomeryx and Palaeomeryx are synonymous; he also proposes the retention of the 
family name Palaeomerycidae expanded to include: 

‘, . . the Old World and New World non-antlered but horned and some hornless 
cervoids. The genera with forked horns from the Old World are included in the 
subfamily Palaeomerycinae and those from North America with pointed, 
bulbous or flat tipped horns are assigned to the Dromomerycinae.’ (Stirton 
1944). 

Whitworth (1958) discusses the affinities of the palaeomerycids at some length, 
supporting the synonymy of Lagomeryx and Palaeomeryx and indicating the close 
affinity of palaeomerycids and cervids. This is contested by Ginsburg and Heintz 
(1966) who challenge the synonymy of Lagomeryx and Palaeomeryx and in their 
discussion of the genus Palaeomeryx they state: 

‘En dehors d’Europe, le genre a été signalé par Teilhard de Chardin (1939) dans 
le Miocéne de Chine et par T. Whitworth (1958) dans le Miocéne d’Afrique 
orientale. Dans les deux cas, on peut affirmer qu'il ne s’agit pas de Palaeomeryx 
ne serait-ce que par la présence, chez deux formes, d’une P}.’ 

The presence of a P; in Palaeomeryx africanus is questioned by Gentry (1970) but 
a P; was certainly present in the species described by de Chardin (1939); which 
must therefore be removed from the genus Palaeomeryx and should revert to its 


132 LOWER MIOCENE RUMINANTS 


previously applied name of Lagomeryx simpsoni ; however the name Lagomeryx is not 
applicable as it was established (Roger 1904) to refer to European species which have 
been synonymized with Palaeomeryx: in this situation the species reverts to its 
original name—Heterocemas simpsoni Young 1937. 

Pilgrim (1941) and de Chardin (1939) indicate close giraffoid affinities for the 
Palaeomerycidae (Lagomerycidae) and their evidence for this was summarized by 
Whitworth (1958): 

‘(i) the unequal development of anterior and posterior external ribs on the 
upper molars; (ii) the characteristically corrugated enamel of the teeth; (111) 
the occurrence of a permanent velvet over the bony parts of the “antlers’’.’ 

Whitworth objected to the first on the grounds that variation occurs in the 
strength of the ribs in both giraffids and cervids and he states: 

‘In fact, an unequal development of the anterior and posterior external nbs 
are found, to a varied degree in most cervids and giraffids alike; although 
generally speaking, the anterior rib is more angular and better defined in the deer 
than in the Giraffidae.” (Whitworth 1958). 

This objection is valid as is his objection to the second piece of evidence on the 
basis of the great variability of the enamel in the molars of the giraffids and cervids. 
The third piece of evidence is the strongest and Whitworth’s grounds for rejecting 
it are correspondingly weak, he states: 

‘Finally to regard the possession of non-deciduous, velvet covered ‘‘antlers’”’ as 
diagnostic of early Giraffoidea is contrary to Pilgrim’s own repeated opinion 
(1941 and 1947) that this was as likely to be the primitive cervoid condition as the 
giraffoid.’ (Whitworth 1958). 

This distinction is probably basic to the classification of the giraffids, cervids and 
palaeomerycids and Pilgrim’s statement is given here: 

‘.. . the skin covered “horn” was the most primitive and the nearest 
approximation to it is to be seen in the Lagomerycid and Giraffid “horn”. 
From this original type it is easy to surmise that the deciduous antlered horn 
of the Cervidae arose, though the intermediate stage is as yet unknown.’ 
(Pilgrim 1941). 

Whitworth indicated that this could just as easily mean that the palaeomerycids 
were primitive cervids as giraffids but the ossicones are positive evidence in favour 
of the affinity of the palaeomerycids and giraffoids, whereas they can only be 
regarded as evidence for the affinity of palaeomerycids and cervids on purely 
hypothetical grounds. In this context Ginsburg and Heintz (1966) state: 

‘Les ossicones de Palacomeryx offrent, avec ceux des Girafes, de si fortes simili- 
tudes que nous nous demandons s’il ne s’agit déja d’un Girafide vrai.’ 

The upper dentition of Zarafa agrees with that of Palaeomeryx in many features 
but it also agrees with Palaeotragus and the skull shows close affinities with the 
palaeotragines. Unfortunately the skull of Palaeomeryx is not known but the 
presence of a dentition with some palaeomerycid features on a skull with giraffid 
affinities indicates the closeness of the palaeomerycids and the giraffids. 

Much of the confusion over the affinities of the palaeomerycids can be attributed 
to the poorly defined limits of the family. Ginsburg and Heintz (1966) have 


GEBEL ZELTEN, LIBYA 133 


removed Walangamia africanus and Heterocemas simpson from the genus Palaeo- 
meryx which limits the genus mainly to the Lower and Middle Miocene of Europe. 
They also suggested the removal of the Oligocene genera which lack ossicones, from 
the Palaeomerycidae, transferring them to a position as the common stock from 
which the giraffids and cervids evolved; this group was named the Dremotheriidae 
by Ginsburg and Heintz but it is of the same status as the other main groups and 
should therefore have superfamily status. This regrouping of the early ruminants 
results in an arrangement as shown (text fig. 12). 

The North American members of the Palaeomerycidae were discussed in detail 
by Stirton (1944) who assigned them to the subfamily Dromomerycinae and indicated 
an origin for this group which was close to the origin of the cervids and palaeomery- 
cines. Simpson (1945) treated the Dromomerycinae as a subfamily of the cervidae; 
while Crusafont (1952) placed the tribe Blastomerycini in the Palaeomerycinae and 
transferred the Dromomerycinae to the Giraffoidea. Ginsburg and Heintz (1966) 
proposed the inclusion of the blastomerycines in the Dremotheriidae. The 
blastomerycines are small, hornless pecorans, at the same level of evolution as the 


OLD WORLD NEW WORLD 
LOWER Cervoidea Dromomerycidae 
MIOCENE 
Blastomerycidae 
UPPER Giraffoidea 
OLIGOCENE 
MIDDLE Dremotheriidae 
OLIGOCENE 
LOWER 
OLIGOCENE 
UPPER Gelocidae 
EOCENE 


Fic. 12. The interrelationships of the early, non-bovid ruminants. 


134 LOWER MIOCENE RUMINANTS 


dremotheriids and, with the exception of Eumeryx, they are an entirely New World 
group. At this level of pecoran evolution the forms are so similar that division into 
groups is difficult and it is proposed that the Dremotheriidae and Blastomerycidae 
should be treated as separate families of the Dremotherioidea. The Dromomerycidae 
probably originated from the Blastomerycidae. 

Eumeryx culminis from the Hsanda Gol Formation was identified (Matthew and 
Granger 1924) as a blastomerycine and was so classified by Simpson (1945), it is the 
only blastomerycine from the Old World and is of Lower Oligocene age whereas 
the other blastomerycines are of Lower Miocene age. Stirton (1944) briefly discussed 
the position of Eumeryx and he states: 

‘As to whether Ewumeryx is placed in the Cervoidea or Traguloidea is more or 
less arbitary but recognition of its pre-cervoid characters is quite important.’ 
(Stirton 1944). 

In view of the great difference of distribution in space and time and the difficulty 
of establishing relationships purely on the dentition, at this level of ruminant 
evolution; the affinity of Eumeryx with the other blastomerycines is doubtful. 

The Pecora probably originated from the Traguloidea during the Upper Eocene or 
Lower Oligocene and of the two traguloid families the Gelocidae are the most 
likely to have given rise to the Pecora. In the gelocids true selenodonty is developed 
from more bunodont forms; thus Lophiomeryx has very bunoid lower molars showing 
few signs of true selenodonty while Bachithertum and Prodremother1um have molars 
which are very similar to those of Dremotherium. A detailed study of this group is 
needed and it is here that the divergence of the Bovoidea and other higher ruminants 
probably occurred. 

The system shown (text fig. 12) appears more natural than any yet proposed for 
the evolution of the early, non-bovid ruminants. The members of the Dremother- 
ioidea appear to form a natural unit and Palaeomeryx with its closely allied genera 
are included in the Giraffoidea. The whole pecoran classification at this level is in a 
state of flux as it relies upon very small differences and only the discovery of more 
localities and more complete material can resolve some of the outstanding problems. 


IV. THE EFFECT OF THE OSSICONES ON GIRAFFOID EVOLUTION 


With the exception of size, the most important differences between Zarafa and 
Prolibytherium are related to the frontal bones, ossicones and occipital region. The 
ossicones of Zarafa were developed supraorbitally and probably projected dorso- 
laterally asin Samotheriwm sinense (Bohlin 1926 pl. VI.). Each ossicone was probably 
a simple, conical projection about the same size as in Okapia. The ossicones of 
Prolibytherium are well known (pl. 7). If the origin of the giraffoids lies in the 
middle or late Oligocene then the divergent trends in the development of the ossicones 
must have been established very early to allow such great differences to evolve by 
the early Miocene; these trends may be revealed by the ossicones. 

Frontal appendages are developed in the ruminants primarily for intraspecific 
combat and certain rules may be applied to their development; these were formu- 
lated by Geist (1965). Fighting in Givaffa (Innis 1958) and Okapia (Walther 1960 


GEBEL ZELTEN, LIBYA 135 


and 1962) consists of lateral display and the delivery of heavy blows to the sides and 
neck of the opponent with the head used as a club. Lateral display is the most 
primitive combat method used in the ruminants and is also found in the tylopods. 
With this combat method strong crushing or bending forces are not experienced 
along the length of the neck and therefore any tendency to increase the length of the 
neck is not inhibited by behavioural factors; indeed increase in length of the neck 
may confer a small selective advantage in combat as the length of the swing and 
therefore the force of the blow will be increased. This slight advantage would rein- 
force advantages resulting from other aspects of the animals behaviour such as 
feeding habits. With this combat method the force of blows delivered is on the 
lateral region of the frontals and therefore if a protuberance is developed it will be 
primitively in the supraorbital position; also head to head contact will not usually 
occur and a skin covered appendage will be effective and will retain its skin covering 
at least over most of its surface as in Givaffa or Okapia. Apart from the extant 
girafids many of the palaeotragines and giraffines were long necked relatively 
slender animals, with small ossicones and it is likely that lateral combat methods were 
practised by all of them. 

In Prolibytherium the ossicones consist of a solid outer layer of bone and a cancellous 
interior; frontal sinuses are not present. The derivation of the ossicones in Proliby- 
therium cannot be established but certain features of the skull may indicate their 
mode of origin. The anterior palmation projects antero-laterally from the supraorbital 
region and it is possible that the anterior region was derived from a supraorbital tine 
similar to that of Zarvafa. At the posterior end of the ossicones the presence of 
paired pillars (pl. 10, fig. 2) suggests the derivation of this region from paired 
supraoccipital ossicones. The occurrence of supraorbital and parietal ossicones in 
other sivatheriids and palaeotragines indicates that giraffoids have the ability to 
develop ossicones in both regions. 

The ossicones of Prolibytherium are the earliest advanced frontal appendages known 
in the ruminants. Geist (1965) relates the evolution of large frontal appendages 
to intraspecific combat involving frontal or head to head attack with wrestling and 
pushing between the heads. Geist states: 

“.. . cervid antlers should be regarded primarily as structures binding 
opponents together during pushing and wrestling matches.’ 

Thus the ossicones of Prolibytherium present a stage of evolution which is more 
advanced than that of Zavafa. The ossicones would also function in threat postures 
with reference to which Coope (1968) states: 

‘I believe that initially the “‘pedicels’’ evolved as threat display structures 
increasing the apparent surface area of the face and thus its deterrent value.’ 

Geist and Coope agree that the frontal appendages function in frontal display and 
attack when they are large and the effectiveness of the ossicones of Prolibytherium in 
increasing the apparent surface area of the face cannot be questioned. 

Morphological and functional differences between the ossicones of Zarafa and 
Prolibytherium may suggest reasons for the divergence between the two main lines 
of giraffoid evolution. The selective advantage in intraspecific combat conferred 
by the large ossicones of the sivatheriids was a strong evolutionary force maintaining 


136 LOWER MIOCENE RUMINANTS 


the large ossicones and also the short neck and limbs necessary for their effective use. 
The more primitive combat methods of the palaeotragines and giraffines tended to 
increase the selective advantage of a long neck and, more important, made possible 
the elongation of the neck under other selective forces. 


V. A CLASSIFICATION OF THE GIRAFFOIDEA 


The discovery of Prolibytherium and Zarafa in the Burdigalian of North Africa 
indicates that the origin of the giraffoids must lie in the late Oligocene and that 
divergence within the group occurred at this time. This was also stated by Ginsburg 
and Heintz (1966): 

‘On peut se demander si les soi-distant Cervides sans bois de la fin de l’Oligocene 
(Amphitragulus, Dremotherium, Blastomerycines) ne representant pas, non 
des Cervides primitifs, mais le stock commun d’ou sortiront a l’epoque suivant 
les Cervides, d’une part, et les Giraffoidea, d’autre part.’ 

Features of Zarafa and Prolibytherium indicate divergence very soon after their 
origin from the pregiraffoid stock and the establishment of a separate family to 
accommodate the sivatheres is proposed. The evolution of the giraffines and palaeo- 
tragines has followed similar trends and the divergence of these two groups probably 
did not occur until the middle Miocene, they are therefore retained as subfamilies 
within the family Giraffidae. This results in a classification of the Giraffoidea as 
summarized in text figure 13. 


Superfamily GIRAFFOIDEA Simpson 1931 
Family PALAEOMERYCIDAE Lydekker 1883 


Canthumeryx New genus. L. Miocene; Africa. 
Climacoceras MacInnes 1936. M-—U. Miocene; Africa. 
Heterocemas Young 1937. U. Miocene; Asia. 
Palaeomeryx Von Meyer 1834. L. Miocene; Africa. 
M-U. Miocene; Europe. 
Procervulus Gaudry 1878. L—M. Miocene; Europe 
Propalaeoryx Stromer 1926. L. Miocene; Africa. 
Triceromeryx Villalta, Crusafont and Lavocat 1946. 
L. Miocene; Europe. 
Incertae sedis. 
Progivaffa Pilgrim 1908.  L. Miocene; Asia. 

The Palaeomerycidae. At present the family is best regarded as a level of ruminant 
evolution equivalent to the primitive representatives of the Giraffidae and Sivatherii- 
dae. This system was used quite drastically by Stirton (1944) who drew straight 
lines across his phylogenetic diagram to indicate levels of evolution and the limits of 
the family. 

The genus Tviceromeryx is placed in the Palaeomerycidae as it shows close similari- 
ties to the members of the genus Palaeomeryx from Sansan. The presence of a 


GEBEL ZELTEN, LIBYA 137 


supraoccipital horn sets it apart from the other palaeomerycids and, owing to its 
strange nature, from all the sivatheriids and giraffids; however the material of 
Triceromeryx can be interpreted differently and it is possible that the supraoccipital 
ossicone does not belong to Tviceromeryx, this is also suggested by Churcher (1970). 
The lower dentition of Tviceromeryx is very palaeomerycine in form and each molar 
bears a strong ‘Palaeomeryx fold’. The P4 is almost indistinguishable from a Py, of 
Palaeomeryx sansaniensits (M.5409). The presence of a ‘Palaeomeryx fold’ is not 
evidence of palaeomerycid affinities as such a fold is also present in some specimens 
of Palaeotragus and Honanotherium but in these genera the occurrence of the fold is 
irregular. The genus Tviceromeryx is endemic to the Iberian peninsula and certainly 
does not effect the evolution of the advanced giraffoids. 

The main problems relating to this family cannot be resolved until an exhaustive 
review of the European material is made. It is unlikely that the palaeomerycids 
gave rise to either of the other giraffoid families or to the cervids. They represent 
a Miocene expansion of the ruminants into an ecological niche which was later filled 
by the palaeotragines and cervids. Inter-relationships within the family are not 
known. 


LOWER 
PLIOCENE Palaeotraginae Giraffinae Sivatheriidae 
UPPER 
MIOCENE 
MIDDLE 
Giraffidae 
MIOCENE 
LOWER 
MIOCENE Palaeomerycidae arafa Prolibytherium 
UPPER 
OLIGOCENE 
Dremotheriidae 
MIDDLE 
OLIGOCENE 


Fic. 13. The early evolution of the Giraffoidea. 


138 LOWER MIOCENE RUMINANTS 


Family SIVATHERIIDAE New family 


Birgerbohlinia Crusafont 1952. L. Pliocene; Europe 
Bramatherium Falconer 1845. M. Pliocene; Asia. 
Helladotherium Gaudry 1860. L. Pliocene; Europe, Asia, 
and N. Africa. 
Hydaspitherium Lydekker 1878. M. Pliocene; Asia. 
Libytherium Pomel 1893. U. Pliocene and Pleistocene; Africa. 
Prolibytherium Arambourg 1961. L. Miocene; Africa. 
Sivatherium Falconer and Cautley 1835. U. Pliocene and 
Pleistocene; Asia. 


SIVATHERIIDAE: Prolibytherium is the earliest representative of this family but 
even in this genus the ossicones are highly developed and the cheek teeth show 
hypsodont tendencies. The retention of a lacrymal fossa indicates the primitive 
nature of the genus. The family is characterized by its short neck and limbs, and 
also by the large ossicones; these are probably related features but they also indicate 
that members of the family fed near the ground and grazing forms may have 
developed. Meladze (1964) suggests that the family reached its climax in the late 
Miocene but I would place this climax in the Pliocene when the group was represented 
by fairly abundant, massively built forms throughout the Old World. The African 
genus Libytherium is probably the only Upper Pliocene and Pleistocene genus from 
Africa and with it may be synonymized such forms as Griquatherium Cooke and Wells 
1947 and Ovangiotherium van Hoepen 1932. The genus Helladotherium from 
Pikermi, is problematical as it lacks ossicones, indicating that it was probably the 
female form: with reference to this genus Matthew (1929) states: 

‘It appears not at all improbable that Helladotherium may be the female of 
Bramatherium or Hydaspitherium. The teeth are indistinguishable, and the 
skulls are by no means as diverse in degree, but differ in the same manner, as 
Sivatherium and “Indratherium” of the Upper Siwaliks.’ 

No further work has been done on this problem and Helladotherium is here included 
in the family as a valid genus, with the qualification that it is probably a female 
form. 

Meladze (1964) also suggests that the sivatheriids were adapted to life in the 
savannahs but I suggest that they were probably woodland or forest forms, feeding 
on low vegetation or grasses of the woodland floor. The family was very successful 
and it may have survived in Asia to sub-recent times as suggested by Colbert (1936). 


Family GIRAFFIDAE Gray 1821 
Subfamily PALAEOTRAGINAE Pilgrim 1911 


Givaffokeryx Pilgrim 1910. L. Pliocene; Asia. 
Okapia Lankester Ig01. Pleistocene and Recent; Africa. 
Palaeotragus Gaudry 1861. U. Miocene; Europe, Asia, 
and Africa. L. Pliocene; Europe 
and Asia. 


GEBEL ZELTEN, LIBYA 139 


Samotherium Major 1888. U. Miocene; Africa. L. Pliocene 
Europe and Asia. 
Zarafa New genus. L. Miocene; Africa. 


Subfamily. GIRAFFINAE Zittel 1893. 


Bohlinia Matthew 1929. L. Pliocene; Europe. 

Decennatherium Crusafont 1949. L. Pliocene; Europe. 

Givaffa Brisson 1756. Pliocene; Europe and Asia. 
Pleistocene; Asia and Africa. 
Recent; Africa. 

Honanotherium Bohlin 1926. Pliocene; Asia. 


GIRAFFIDAE: A group of late Oligocene origin with Zarafa as the earliest known 
genus. The family is characterized by a tendency to increase the length of the neck 
and limbs. The giraffids reached their climax in the early Pliocene when they were 
well represented throughout the Old World. It was probably during the middle 
Miocene or slightly earlier that the group divided into two subfamilies; the palaeo- 
tragines and giraffines. 

The palaeotragines were in many ways very progressive and the development of a 
hypso-brachyodont dentition in later members of the genera Palaeotragus and 
Samotherium indicates that they probably fed upon fairly low vegetation with a high 
proportion of ground vegetation in their diet. In any case they were utilizing an 
intermediate zone between the bovids and giraffines and in times of scarcity it is this 
zone which the other two groups would utilize at the expense of the palaeotragines. 
The subfamily has one extant member, the okapi which has survived in a tropical 
forest environment. 

The giraffines have been relatively successful since the Pliocene. The series 
Honanotherium, Bohlinia, Givaffa suggested by Bohlin (1935) seems to be a natural 
sequence and is probably the true relationship. 


VI. EAST AFRICAN RUMINANTS 


During this work reference has been made to the Miocene ruminants of East 
Africa which were described by Whitworth (1958). A brief review of these ruminants 
has been made as I disagree with some of Whitworth’s identifications. These 
ruminants are treated as a separate section as they are nearly all previously described 
forms and all depend upon previously described material; also it was felt that their 
inclusion with the Libyan forms would confuse the description of a regionally defined 
ruminant group. 


Superfamily TRAGULOIDEA Gill 1872 
Family TRAGULIDAE Milne-Edwards 1864 
Genus DORCATHERIUM Kaup 1833 


The agreement between Dorcatherium chappuisi from Rusinga and Turkana 
(Arambourg 1933) is very close and there is no doubt that these specimens are from 


140 LOWER MIOCENE RUMINANTS 


the same species. The other three species described by Whitworth (1958) are 
D. pigotti, D. parvum and D. songhorensis ; these are distinguished on a size basis 
only and with reference to these species Whitworth states: 
‘Further collecting may show that D. songhorensis is synonymous with D. 
parvum or D. pigotti, but for the present it seems preferable to treat the Songhor 
material separately.’ (Whitworth 1958). 

I agree with Whitworth on this point, there are certainly two smaller species of 
Dorcatherium and as further collections have not been made it is not possible to 
synonymize D. songhorensis with either of these. 

The genus Dorcatherium is the only traguloid genus previously identified from the 
Miocene of Africa but included in the material identified as Palaeomeryx africanus 
(Whitworth 1958) are a few lower molars which differ anatomically from the type 
specimen. These molars exhibit traguloid features and agree closely with the lower 
molars of Gelocus. 


Superfamily TRAGULOIDEA Gill 1872 
Family GELOCIDAE Schlosser 1886. 


DiacGnosis: Traguloids in which true selenodonty is developed; strong cingula 
developed on the labial or lingual sides of the cheek teeth. Metapodials fused to 
form cannon bones and side toes reduced. Lower premolars very simple. Pj 
reduced and peg-like, separated from Pz: by a short diastema (After Schlosser 
1886). 


Genus GELOCUS Aymard 1855 


Diacnosis: A medium sized gelocid in which the selenodonty is less advanced 
than in most members of the family. Metaconid rounded anteriorly but less so 
than in Lophiomeryx. Premolars very simple. (Mainly after Schlosser 1886). 


Gelocus whitworthi sp. nov. 


Diacnosis: A medium sized species of Gelocus possessing a rounded metaconid on 
the lower molars; the median valley of the lower molars is very open lingually. 
Length of lower molar row about 33 mm. 


SYNONYMY: One specimen of this species—K.Sgr.368.49—was described by 
Whitworth (1958) with Palaeomeryx africanus. 

DERIVATION OF NAME: The species is named after Dr. T. Whitworth who produced 
the first definitive account of African Miocene ruminants. 

Ho.otyPe: K.Sgr.365.1949—a left mandibular fragment with lightly worn Me 
and Ms. From Songhor, Nyanza Province, Kenya. All specimens of this species 
are the property of the National Museum, Kenya. 


GEBEL ZELTEN, LIBYA 141 


LOCALITY AND HORIZON: Specimens are from Songhor and Rusinga Island Kenya. 
Both sites are referred to the Miocene. 


MATERIAL: 
K.Sgr.265.1949 Holotype; a left mandibular fragment with lightly worn Me 
and M3. 
K.Sgr.368.1949 An isolated M, showing slightly heavier wear than the 
holotype. 


K.Sgr.581.1949 An isolated right Mg showing light wear. 
K.Sgr.159.1949 An isolated right Mz showing medium wear. 
K.R.30 An isolated right M3, showing medium wear. 


DeEscriPTIoNn: The lower molars are almost the same size as Walangania africanus. 
On the Mz the metaconid is conical with an anterior crest curving antero-lingually to 
meet the mesostylid at the antero-lingual corner of the tooth; this results in the 
concavity of the antero-lingual face of the metaconid similar to Gelocus communis 
but differing greatly from Walangania in which the metaconid is selenodont. The 
postero-lingual face of the metaconid is rounded with a feeble metastylid but lacking 
a fold such as is present in Dorcatherium. In Walangania the metastylid lies lingual 
to the anterior end of the entoconid whereas in Gelocus it is closely joined to the 
metaconid and lies lingual to the posterior end of the metaconid; as a result the 
median valley is very open lingually (pl. 13, fig. 5). The entoconid is conical with 
a strong anterior crest. The posterior end of the entoconid is forked and the labial 
branch meets the postero-lingual end of the hypoconid while the lingual branch 
is produced postero-lingually. This results in a strong vertical groove on the 
posterior face of the cuspid (pl. 13, fig. 4); a similar groove is present in Gelocus 
communis in which the lingual branch meets the postero-lingual extension of the 
hypoconid and the labial wing joins this part of the hypoconid. No such groove is 
present in Lophiomeryx, Bachytheriwm or Prodremotherium. 

The protoconid is crescentic and extends antero-lingually around the anterior 
end ot the metaconid; causing the anterior fossette to open lingually (pl. 13, fig. 4) 
but not to the same extent asin Lophiomeryx. The posterior region of the protoconid 
extends lingually and joins the postero-labial face of the metaconid from which a 
wing is produced as in Walangania and Palaeomeryx; however in Gelocus this wing 
is much more anteriorly situated resulting in a shorter anterior fossette and a longer 
median valley region. The anterior wing of the entoconid also meets the protoconid 
in this region. The hypoconid is crescentic and lower than the protoconid. Me 
has strong anterior and posterior cingula. 

The metaconid of M3 is more feeble than on Ms and the anterior crest is weaker. 
In Lophiomeryx the anterior end of the metaconid is extremely shortened and rounded 
while in Gelocus it bears a strong crest and is truly selenodont. The entoconid is 
more selenodont in M3 than Mg, this is mainly due to the presence of a strong crest 
in the posterior region. This crest extends posteriorly and lies lingual to the 
postero-lingual end of the hypoconid (pl. 13, fig. 4). The posterior end of the 
entoconid is not forked as in the Mg; this region is similar to Gelocus communis but 
differs from Lophiomeryx in which the entoconid has only a feeble posterior crest. 


142 LOWER MIOCENE RUMINANTS 


The protoconid is crescentic and its antero-lingual extension is stronger than in the 
Mg; resulting in the posterior shift of the lingual opening of the anterior fossette 
in the M3 relative to the Mg (pl. 13, fig. 4). The hypoconid is similar to that ot the 
Mz but the posterior region is shorter in the Mg as it joins the posterior extension of 
the hypoconid. Theaccessory column consists of a strong entostylid running postero- 
labially from the posterior end of the entoconid and fusing with the strong hypoconu- 
lid. The hypoconulid is crescentic and curves postero-labially from the face of the 
hypoconid (pl. 13, fig. 4). Atits posterior end the hypoconulid turns antero-lingually 
and almost encircles the entostylid. M3 has a strong anterior cingulum and both 
M2 and Mz have strong entostylids in the median valleys. Mg also has a stylid at 
the labial end of the posterior valley. 

Features of their anatomy warrant the specific but not generic separatioa of these 
specimens from other species of Gelocus. Their presence in East Africa is important 
as representatives of the family Gelocidae are previously unrecorded from Africa. 


TABLE 12 


The Lower Dentition of Gelocus whitworthi 


My Me M3 
Length Width Length Width Length Width 
K.Sgr.365.1949 = —_ to-8 mm 67mm 14'7mm 6-9 mm 
K.Sgr.368.1949 975 mm 5:9 mm — — — — 
K.Sgr.581.1949 — — — — 14-5 mm 6-8 mm 
K.Sgr.159.1949 — oo 10-4 mm 6-7 mm — — 
K.R.30 — — — — 15-0 mm 6:38 mm 


Family PALAEOMERYCIDAE Lydekker 1883 
Genus PROPALAEORYX Stromer 1926 


DiaeGnosis: ‘Pecora of medium size, with shallow mandible and rather brachyodont, 
selenodont lower cheek teeth, closed from Pz: to Mg; P isolated by a very short 
diastema. Enamel wrinkled. Lower molars with very strong metastylid and 
entostylid; pronounced median rib on lingual surface of metaconid, similar rib on 
entoconid ; accessory stylid in median, external valley developed to varying degree.’ 
(Whitworth 1958). 


TYPE SPECIES. Pyvopalaeoryx austroafricanus Stromer 1926; from the Lower 
Miocene of South West Africa. 


Propalaeoryx nyanzae Whitworth 1958 


Dracnosis: ‘A species of Propalaeoryx with lower molar series (Mj-3) measuring 
about 45 mmin length. All lower molars have prominent accessory tubercle in the 
median, external valley. Teeth rather lower crowned than in type species, P. 
austroafricanus.’ (Whitworth 1958). 


GEBEL ZELTEN, LIBYA 143 


Ho.otyPpe: M.21368 (K.324.47) Figured Whitworth 1958, fig. 12. A fragment of 
left mandible with Mi and Mg showing slight wear. 


Horizon: From the Lower Hiwegi Beds, Rusinga Island. Lower Miocene. 


MATERIAL: 
M.21368 Holotype. 
K.1263.51 — Isolated left Me. 
K.614.49 Anterior region of right M3. 
K.774.52 Right mandibular fragment with Mz and M3. 
K.780.52 Newly erupted left Ms. 
K.193.51 Heavily worn left M2. 
K.Mt.21 Lightly worn right M1. 
eX. Left maxillary fragment with M1 and M2. 
K.Mt.67.51 Fragment of left maxilla with P4 and M!. (Listed as Palaeomeryx 
africanus by Whitworth 1958; table X.). 
K.246.59 Heavily worn left M1. 


DeEscrIPTION: Whitworth (1958) described the lower dentition only and upper 
molars here identified as Propalaecoryx nyanzae agree with the lower molars in details 
such as size, brachyodonty, degree of rugosity, depth of fossettes and strength of 
labial ribs and styles. The lower dentition is redescribed as it agrees closely with 
Canthumeryx. 

Lower dentition. The enamel of the molars is finely rugose. Moe has a strong 
anterior cingulum as in P. austroafricanus and Canthumeryx; this cingulum has a 
serrated occlusal edge and appears to consist of a series of small tubercles. The 
molars exhibit the same degree of brachyodonty as in Canthumeryx. On the Me 
the posterior crest of the metaconid is flexed labially in the unworn state and this 
flexion is indicated on the wear trace until medium wear has occurred. The lingual 
rib of the metaconid is as strong as that of Canthumeryx but does not equal the strength 
of this rib in Palaeomeryx furcatus or Palaeomeryx magnus in which the rib has a 
strong posterior fold. The metastylid is strong and projects lingually but it is weaker 
than the metastylid of some palaeomerycids. The entoconid is shortened in the 
posterior region and the posterior fossette opens lingually. The protoconid is 
crescentic and joins the anterior end of the metaconid; this end of the molar is very 
pointed as in Canthumeryx (pl. 14, fig. 1). The hypoconid is crescentic and its 
anterior end meets the protoconid in the median valley. The posterior end of the 
hypoconid is very long and is produced lingually. 

The Mz is similar to the Mg in the anterior region. The posterior region of the 
hypoconid is produced lingually and meets the face of the strong entostylid. The 
hypoconulid is crescentic and joins the hypoconid labially and the entostylid lingually 
thus enclosing a large enamel island (pl. 14, fig. I). 

Upper dentition. The molars are four rooted with the lingual and labial pairs of 
roots fused. The enamel is more rugose than in Walangania and M! has a strong 
anterior cingulum and a weaker posterior cingulum. The parastyle of M! is strong 
with a pronounced labial rib which forms the antero-labial corner of the tooth. 
The paracone is stout and less transversely flattened than that of Walangania; this 


144 LOWER MIOCENE RUMINANTS 


is a primitive feature resembling the traguloid condition. The labial rib of the para- 
cone is stronger than that of Walangamnia (pl. 14, fig. 2) and resembles closely that of 
Palaeomeryx in which the rib flexes slightly anteriorly. The mesostyle is similarly 
developed in Propalaeoryx, Walangania and Palaeomeryx. The metacone has a 
feeble labial rib and the metastyle is strongly developed (pl. 14, fig. 2). The protocone 
is similar to that of Palaeomeryx ; it is crescentic with a few small wings at the postero- 
labial end; these project into the medial valley and the anterior fossette (pl. 14, fig. 2). 
The anterior fossette is much shallower than in Walangania but resembles that of 
Palaeomeryx. The metaconule is crescentic; from its posterior region two strong 
accessory crests project into the fossette; these are strongly developed in all the molars 
and an enamel island is formed early in wear, this island is large and shallow (pl. 14, 
fig. 2). As wear continues the first enamel island is lost and a smaller one is developed 
at the posterior end of the fossette. Accessory crests are very feeble when present in 
Walangania. 

M2? is similar to M! in all its main features. Each molar has a strong entostyle 
in the median valley and a very strong anterior cingulum which has a serrated edge 
as in the lower molars. 

The P4 is similar to that of Palaeomeryx. The labial region of the tooth is not 
known but the lingual region of the metacone is preserved. The protocone is 
crescentic and from its posterior region an extremely strong accessory crest divides 
the fossette into anterior and posterior regions (pl. 14, fig. 2); in the posterior region 
a series of small tubercles and folds are present on the face of the protocone and 
metacone. A strong cingulum forms a swelling at the base of the lingual face of the 
protocone (pl. 14, fig. 3) a similar though weaker cingulum is occasionally present in 
Palaeomeryx and Walangania. 

The upper dentition with its shallow fossettes, stout labial cusps, strong styles and 
cingula and complications of the cusps by accessory crests or tubercles is more primi- 
tive than the dentition of Palaeomeryx or Walangania and in many features agrees 
closely with the tragulid dentition. The description of the upper molars of Propalae- 
oryx shows that though it is more primitive than Palaeomeryx it shows closer affinities 
with this type of dentition than with the primitive bovids. 

The affinities of Propalaeoryx. Stromer (1926) indicated that Propalaeoryx was a 
member of the Bovidae but Arambourg (1933) states: 

‘Propalaeoryx austro-africanus Stomer appartient a une espéce d’assez grande 
taille et posséde d’incontestables traits de Cervidé primitif.’ 

Whitworth (1958) discusses the affinities of Propalaeoryx and states: 

‘Indeed in everything except size, the lower molars of Propalaeoryx are precisely 
like those of Micromeryx from the Miocene of Europe.’ 

In spite of evidence presented by dentition, Whitworth continues his argument, 
citing isolated ruminant limb bones which he tentatively identifies as Propalacoryx ; 
especially a single metatarsal which: 

‘“. . . exhibits a bovid condition in the housing of the extensor tendon while 
retaining a remarkably cervid-like development of the shaft.’ (Whitworth 
1958). 

The reasons for this identification rest upon the fact that the bone agrees in size 


GEBEL ZELTEN, LIBYA 145 


with Propalaeoryx nyanzae; however true bovid dentitions of a similar size have 
been found in these deposits. Whitworth considered this single bone to be sufficient 
to cast grave doubts on the supposed cervid affinities of the genus but I do not feel 
that this tentative evidence can outweigh positive evidence presented by the dentition 
in favour of palaemerycid affinities for Propalaeoryx. As stated the dentition of 
Propalaeoryx is similar to that of Palaeomeryx and the strong metastylid, which is 
much stronger than that of Walangania, is a palaeomerycid rather than a bovid 
character. The lower premolars of Propalaeoryx austroafricanus are virtually 
indistinguishable from those of some palaeomerycids or from Canthumeryx. For 
these reasons Propalaeoryx is classified as a member of the Palaeomerycidae. 

It is possible that Canthumeryx and Propalaeoryx are representatives of a new group 
of ruminants which is of African origin but in the absence of more material I prefer 
to group them with an existing and certainly closely related family. 


TABLE 13 
The Dentition of Propalaeoryx nyanzae 


Lower Dentition 


Mi Me Ms 
Length Width Length Width Length Width 
B.M.21368 13°6 mm 72mm 13°7mm 7-9 mm — — 
K.614.49 — -- —- — -- 8-4 mm 
K.1263.51 12°5 mm 7-7 mm — — 
K.774.52 13-5 mm 78mm 19:0 mm 8-3 mm 
K.780.52 —_ o— 19-6 mm 8-2 mm 
Upper Dentition 
p4 M1 M2 
Length Width Length Width Length Width 
K.193.51 —— —- — — 125mm 13:1 mm 
K.Mt.21 - — I4;2mm 14:4 mm — — 
K.X. — _- 13z0mm 14:°0mm 12:0mm — 
K.Mt.67.51 Ioomm 115mm 125mm 13:1 mm — ase 
K.246.59 — — 125mm 14:0mm — — 


BOVIDAE Incertae Sedis 
Genus WALANGANIA Whitworth 1958 


DracGnosis: Small, lightly constructed pecoran. Frontal appendages unknown. 
Mandible with prominent angle and large recurved coronoid process. Cheek teeth 
closed from Pg to Mg. First premolar lost. Lower molars brachyodont, selenodont 
and narrow. Protoconid and hypoconid angular and compressed antero-posteriorly. 
Upper molars square, brachyodont and selenodont. Paracone with strong labial 
rib, metacone lacking labial rib. Enamel of cheek teeth finely rugose. Pelvis and 
rear limbs of advanced pecoran type. (After Whitworth 1958). 


146 LOWER MIOCENE RUMINANTS 


Walangania africanus (Whitworth) 1958 


Palaeomeryx africanus Whitworth 1958. 
Walangania gracilis Whitworth 1958. 
Kenyameryx africanus Ginsburg and Heintz 1966. 


DiacGnosis: As for genus. 


REMARKS: The species Palaeomeryx africanus was established on the basis of a 
large number of upper and lower dentitions as well as a considerable amount of post- 
cranial material. Ginsburg and Heintz (1966) removed the species from the genus 
Palaeomeryx on the basis of a supposed presence of a P; and the more primitive nature 
of the anterior premolars. The name Kenyameryx was suggested to accommodate 
the species. The presence of a Pj was disputed by Gentry (1970) who identifies the 
P; as a second deciduous premolar. 

The genus Walangania is known from the holotype only ; this is an almost complete, 
associated skeleton in which the deciduous dentition and the first permanent molars 
are erupted. Except in the degree of wear the permanent molars are indistinguish- 
able from those which Whitworth described as Palaeomeryx africanus. Although 
Whitworth states that the ‘Palaeomeryx fold’ 1s absent in the holotype a fold is 
certainly present and is as strong as in many specimens of Palaeomeryx africanus. 
The dimensions of the teeth are also very similar in Walangania and Palaeomeryx 
africanus (table 14). 

The main differences in the diagnoses of Walangania gracilis and Palaeomeryx 
africanus are the presence of a P; and a ‘Palaeomeryx fold’ in P. africanus but neither 
of these differences are acceptable on closer investigation. The other differences 
between the species result mainly from the juvenile condition of the Walangania 
holotype and are insufficient to warrant the continued separation of the two species. 

Palaeomeryx africanus was described earlier in the publication than Walangamia 
gracilis but the generic name Palaeomeryx is not applicable to the material. The 
name Kenyameryx suggested by Ginsburg and Heintz (1966) cannot be used as the 
name Walangania has precedence. The trivial name ‘africanus’ is retained as it has 
page precedence over the trivial name ‘gracilis’. 

The affinities of Walangania africanus. The affinities of Walangania gracilis 
were discussed by Whitworth (1958) who concludes: 

‘For the present, Walangania must be regarded as a pecoran genus of doubtful 
systematic position, although the available evidence may slightly favour 
inclusion with the Cervidae.’ 

The affinities of Palaeomeryx africanus were implied by its generic name and there- 
fore with the synonymy of P. africanus and W. gracilis the affinities of the species 
Walangania africanus should lie with the Palaeomerycidae; however a study of the 
material indicates that even this affinity is very doubtful. 

The lower molars of Walangania exhibit weak lingual ribs and styles these agree 
in strength with those of Eotvagus and are weaker than is usual in Palaeomeryx. 
The metaconid and entoconid are aligned almost parallel to the long axis of each 
lower molar in Walangania and Eotragus but in Palaeomeryx these cuspids usually 
have a diagonal orientation. The metaconids and entoconids of the lower molars 


147 


GEBEL ZELTEN, LIBYA 


wu o.FT UIWI O-€T wut o.F1 
WI 9-6 WU O-OT wut S.or 
WU O-II wu $.1T wiur S-11 
UIPIM qysueT TIPIM. 
el 2IN 


IN 


wu O-7I 


uur S.or 
urut $.11 


yysueT 


wut €-11 


UIUI O-ZI 
UIUI O-ZI 
yysue'T 


WU O-€T 


UIUWI I-OL 
UWIUI 0-6 
UIW O-OL 
wut €-6 


UIPIM 


TIN 


uu o.Z 


WIUI 0-9 
wut +.9 
WIUL 9-9 
wut £-9 

UFPIM 


wu O-O1 


uu £-01 
mut £-6 
wut ¢-o1 
UIUL 9-6 
yy8ueT 


TA 


wu F-o1 


WIUI O-II 
wut S.1r 
ww S-Ir 
UIUI O-II 


yy8ueT 


UIUI O-OT 


wut /.g 
WU 9-8 
WIUI 9-8 

UFPIM 


(‘S2719DA8 Diunsuny YY Se poaystT st b Ioquiny) 


rd 


(zS6r sniueyy ur101,7) 
sisuatupsuns snsvuyoq (S) 
ggtie we (%) 

6S€iz wa (€) 
(edAjojoH) gSE1z Wg (Zz) 
Lb-gh-185°y (1) 


uoyyuag samoT 
wu $.9 
(zS6r sntusyy, wo1q) 
sisuatupsuns snsvoyoq (S 


) 

= 6g€iz Wa (F) 
UI 9-9 Lv‘ LeSsy (€) 
wut 2.2 L¥-469'°x1 (Zz) 
UIUI 0-8 6b-Lz'18S yf (1) 


yysueT 


uoyyuag saddyQ 


(‘snuvaiafo xhaamoanjog se ‘gS6x yy1ompY AA Aq pozst] ore € 0} I sroquInN) 


SnUDILA{D DIUDSUDID AA JO WOIZI}UEp OUT, 


vI ATAVE 


148 LOWER MIOCENE RUMINANTS 


tend to be more selenodont in Walangania and Eotragus than in Palaeomeryx. 
The labial ribs and styles of the upper molars are far weaker in Walangania and 
Eotragus than in Palaeomeryx. In all these features Walangamia and Eotragus agree 
and each differs from Palaeomeryx, the main feature in which Palaeomeryx and 
Walangania agree is the presence of a ‘Palaeomeryx fold’ on the lower molars of 
both genera; such a fold is unknown in the bovids but occurs in most other primitive 
ruminants, its presence in Walangania is insufficient to debar this genus from affinity 
with the bovids. 

Gentry (1970) has also suggested bovid affinities for Walangania on the basis of its 
mandibular ramus and he states: 

‘It also has a moderately deep ramus, so it is quite possible that it will one day 
be shown to be a bovid.’ 

The distinction between bovoids, giraffoids and cervoids is very difficult in species 
of Burdigalian age but the dentition of Walangamia exhibits features which indicate 
affinity with early bovids and for this reason it is here treated as a bovid; however all 
the features used exhibit variation and the tentative nature of these interpretations 
must be emphasized. 


VII. REFERENCES 


ARAMBOURG, G. 1933. Mammiféres miocénes du Turkana. Annis Paléont., Paris, 22 : 1-26, 
5 figs, pls. 1-2. 

1947. Mission Scientifique de l’?Omo 1932-1933. Tome 1. Géologie—Anthropologie. 
Muséum National d’ Histoive Naturelle, Paris, 231-562 : 91 figs, pls 1-11. 

1961a. Prolibytherium magmeri, un Velléricorne nouveau du Burdigalien de Libye. (Note 
préliminaire). C. v7. Séanc. Soc. géol. Fy., Paris, 1961 (3) : 61, 1 fig. 

1961b. Note préliminaire sur quelques Vertébrés nouveaux du Burdigalien de Libye. C. 
vy. Seanc. Soc. géol. Fr., Paris, 1961 4. 107, I fig. 

1963a. Legenre Bunolistriodon Arambourg 1933. Bull. Soc. géol. Fr., Paris, (7), 5,903—911, 


Brags i ple 
1963b. Continental vertebrate faunas of the tertiary of North Africa. Jn Howell, F. C. 
and Bourliere. African ecology and human evolution, Chicago, 1963.: 56-63. 


ARAMBOURG, C. & MAGNIER, P. 1961. Gisements de Vertebres dans le bassin tertiaire de 
Syrte (Libye). C. 4. Acad. Sci., Paris, 252 (8) : 1181-1183. 

Brack, D. 1915. A study of the endocranial casts of Okapia, Givaffa, and Samotherium, with 
special reference to the convolutional pattern in the family Giraffidae. J. comp. Neurol., 
Philadelphia, 25, 4 : 329. 

Boutin, B. 1926. Die Familie Giraffidae. Palaeont. Sin., Peking, Ser. C, 4, (1), 1-179, 252, 

figs, pls 1-12. 

1935. Some remarks on fossil Giraffidae. Bull. geol. Soc. China., Peking, 14, 83-89, pl. 1. 

CHARDIN, T. de. 1939. The Miocene Cervids from Shantung. Bull. geol. Soc. China., Peking, 
19 (3) : 269-278, 5 figs. 

CHURCHER, C. S. 1970. Two new Upper Miocene Giraffids from Fort Ternan, Kenya, East 
Africa : Palaeotvagus primaevus n.sp. and Samotherium africanum n.sp. In Leakey & 
Savage 1970. Fossil Vertebrates of Africa. 2. 336p. 

CLarK, Le Gros. 1939. The Brain of the Okapi. Proc. zool. Soc. Lond., 109 B., 153-159, 
4 figs. 

CoLBERT, E. 1933. A skull and mandible of Givaffokeryx punjabiensis, Pilgrim. Am. Mus. 

Novit., New York, 632, 1-14, 6 figs. 

1935a. Distributional and Phylogenetic Studies on Indian Fossil Mammals. V. The 
classification and the phylogeny of the Giraffidae. Am. Mus. Novit., New York, 800, 1-15. 


GEBEL ZELTEN, LIBYA 149 


CoLBERT, E. 1935b. Siwalik Mammals in the American Museum of Natural History. Tyan. 
Am. phil. Soc., Philadelphia. N.S., 26,x + 401 pp. 198 figs. 
1936. Was the extinct giraffe Sivatherium known to the Ancient Sumerians? Am. 
Anthrop., 38. 
1938. The Relationships of the Okapi. J. Mammal., Baltimore, 19, (1), : 47-64, 3 figs. 
CooprE, G. R. 1968. The Evolutionary Origin of Antlers. Deer, 1: 215-217. 
CrusaFont, M. 1952. Los Jirafidos Fésiles de Espana. Mems. Comun. Inst. geol., Barcelona, 
8 : 9-239, 26 figs, pls 1-47. 
Desio, A. 1935. Studi geologici sulla Cyrenaica, sul Deserto Libico, sulla Tripolitania e sul 
Fezzan Orientali. Missione scient. R. Acc. d'Italia a Cufra (1931). I. Rome. 
FRASER, F.C. 1951. Vestigial metapodials in the Okapi and Giraffe. Pyvoc. Zool. Soc. Lond., 
121 : 315-317, pls 1-2. 
Geist, V. 1965. The evolution of horn-like organs. Behaviour. 27, 175-214, 16 figs. 
Gentry, A. W. 1964. Skull Characters of African Gazelles. Ann. Mag. nat. Hist., London 
(13) 7: 353-382. 
1966. Fossil Antilopini of East Africa. Bull. Br. Mus. nat. Hist. (Geol.) London, 12 : 
45-106, 15 figs. 
1970. The Bovidae (Mammalia) of the Fort Ternan Fossil Fauna. In Leakey & 
Savage 1970. Fossil Vertebrates of Africa. 2. 3306p. 
GinspurGc, L. & Herntz, E. 1966. Sur les affinités du genre Palaeomeryx (Ruminant du 
Miocéne européen). C. R. Acad. Sc., Paris, 262 : 979-982, 1 fig. 
Innis, A. C. 1958. The behaviour of the giraffe, Givaffa camelopardalis, in the Eastern 
Transvaal. Proc. zool. Soc. Lond., 131, (2) : 245-278, 6 figs, pl. 1. 
LANKESTER, E. R. 1907. The origin of the lateral horns of the giraffe. In foetal life on the 
area of the parietal bones. Proc. zool Soc. Lond., 1907 : 100-115, figs 24-36. 
1908. On certain points in the structure of the cervical vertebrae of the Okapi and the 
Giraffe. Proc. zool. Soc. Lond., 1908 : 320-324, figs 60-70. 
tg10. Monograph of the Okapi. Bvit. Mus. Nat. Hist., London, 12 pp., pls 1-48. 
LYDEKKER, R. 1883. Siwalik Selenodont Suina. Pal. Indica. (10), II, Pt. 5, 142-177, 
3 figs, pls 23-25. 
MacInnes, D. 1936. A new genus of fossil deer from the Miocene of Africa. J. Linn. Soc. 
London, 39 : 521-530, 5 figs. 
Macanier, P. 1962. Etude géologique du gisement de Vertébrés du Gebel Zelten (Libye). 
C. vy. somm. Séanc. Soc. géol. Fy. Paris, 1962, 2, Feb. 19 : 55-57, I fig. 
MattHew, W.D. 1929. Critical Observations upon Siwalik Mammals. Bull. Am. Mus. nat. 
Hist., New York, 56 : 437-560. 
MattHew, W. D. & GRANGER, W. 1924. New Insectivores and Ruminants from the Tertiary 
of Mongolia, with Remarks of the Correlation. Am. Mus. Novit., New York. 105: 7p 
figs I-3. 
Meap, C. S. 1906. Adaptive Modifications of the Occipital Condyles in Mammalia. Am. 
Nat., Cambridge, Mass., 40 : 475-483, 12 figs. 
Merapze, G. K. 1964. On the phylogeny of the Sivatheriinae. Int. Geol. Congress., 22. 
Reports of Soviet Palaeontologists. (8) Tertiary Mammals. (In Russian). 47-50, 1 fig. 
MILNE-EpDwarps, A. 1864. Recherches anatomiques, zoologiques et paléontologiques sur la 
famille des chevrotians. Ann. Sci. nat. Zool., Paris (5) 2 : 49-167, pls 2-12. 
Piterim, G. 1937. Siwalik Antelopes and Oxen in The American Museum of Natural History 
Bull. Am. Mus. nat. Hist., New York, 72 : 731-874, 81 figs. 
1939. The fossil Bovidae of India. Mem. geol. Surv. India., Calcutta. 26 (1) : iii + 356 
Pp., 35 figs, pls 1-7. 
1941. The Relationship of certain Variant Fossil Types of ‘Horn’ to those of the Living 
Pecora. Ann. Mag. nat. Hist., London, (2), 7 : 172-184. 
Rieu, E. V. 1959. Apollonius of Rhodes. The voyage of Argo. Penguin. London. 
RoGeEr,O. 1904. Wirbeltierreste aus dem Obermiocan der bayerisch-schwabischen Hochebene. 
Ber. naturw. Ver. Schwaben, Ausburg, 36 : 1-22 pls. 1-4. 


150 LOWER MIOCENE RUMINANTS 


Roman, F. & VirET, J. 1934. La faune de Mammiferes du Burdigalien de la Romieu (Gers). 
Mem. Soc. géol. Fr., Paris, (N.S.) 9 (mém 21) : 1-67, pls I-12. 

SavaGE, R. & WuitE, M. 1965. Two mammal faunas from the early Tertiary of central 
Libya. Proc. geol. Soc., London. 1623: 89-91. 

ScHLossER, M. 1886. Beitrage zur Kenntnis der Stammesgeschichte der Hufthiere und 
Versuch einer Systematik der Paar- und Unpaarhufer. Morph. Jb., Leipzig, 12 : iv + 136, 
pls 1-6. 

SELLEY, R. 1968. Near-shore marine and continental sediments of the Sirte basin, Libya. 
Proc. geol. Soc., London. 1648: 81-90, 1 fig. 

1969. Near-shore marine and continental sediments of the Sirte basin, Libya. Q. Jl. 
geol. Soc. Lond., 124 : 149-460, 17 figs, pls 21-25. 

SHUTTLEWORTH, A. 1943. The function of the femoro-patellar joint of the horse. Jl. R. Aymy 
vet. Cps., Aldershot, 15 : 2-6. 7 figs. 

SIGOGNEAU, D. 1968. Le genre Dremotherium (Cervoidea) anatomie du crane, denture et 
moulage andocranien. Annis. Paléont., Paris, (Vertébrés) 54 (1) : 37-64, 33 figs, pls 1-6. 

Simpson, G. G. 1931. A new classification of mammals. Bull. Am. Mus. nat. Hist., New 

York, 59 : 259-293. 
1945. The principles of classification and a classification of mammals. Bull. Am. Mus. 

nat. Hist., New York, 85: xvi + 350. 

Sisson, S. & GROSSMAN, J. 1953. The anatomy of the domestic animals. Fourth Edition, 
Saunders, London, : 972 pp., 736 figs. 

SmitH, J. & SavaGE, R. 1956. Some locomotory adaptations in mammals. J. Linn. Soc. 
London, 42 : 603-622, 14 figs. 

STiRTON, R. 1944. Comments on the relationships of the cervoid family Palaeomerycidae. 
Am. J. Sci., New Haven, 242 : 633-655, 2 figs. 

STROMER, E. 1926. Reste Land- und Siisswasser-Bewohnender Wirbeltiere aus den Diaman- 
tenfeldern Deutsch-Siidwestafrikas. Jn Kaiser, E. Die Diamantenwuste Sudwest-africas, 
2: 107-153. Berlin. 

THENIUS, E. 1952. Die Boviden des steirischen Tertiars. Sbev. Ost. Akad. Wiss., Vienna, (1) 

161, 409-439, 11 figs. 

1956. Zur Entwicklung des Knochenzaptens von Protvagocerus Deperet (Bovidae, 

Mammalia) aus dem Miozan. Geologie, Berlin, 5: 308-318, 5 figs. 

TroFimov, B. 1958. New Bovidae from the Oligocene of Central Asia. Véerteby. palasaat., 
Peking, 2: 244-247, 1 fig. 

VooruiEs, M. R. 1969. Taphonomy and Population Dynamics of an Early Pliocene Verte- 
brate Fauna, Knox County, Nebraska. Contrib. to Geol. University of Wyoming, Special 
Paper. Laramie, Wyoming; 1: 1-69: 29 figs. 

WALTHER, F. 1960. ‘Antilopenhafte’ Verhalfensweisen im Paarungszeremoniell des Okapi 

(Okapia johnstoni Sclater, 1901). Z. Tierpsychol., Berlin, 17 : 188-210. 

1962. Uber ein Spiel bei Okapia johnstoni. Z. Saugetierk., 27 : 245-251. 

WesB, D. 1965. The osteology of Camelops. Bull. Los. Ang. City. Mus. Sci., Los Angeles, 
1: 1-54, 22 figs. 

WEBER, 1928. Die Sdugetiere. Einfuhrung in die Anatomie und Systematik der Recenten 
und Fossilen Mammalia. Gustav Fischer, Jena, pt 1: xv—444, 315 figs pt 2: xxiv + 
898, 573 figs. 

WHITWoRTH, T. 1958. Miocene Ruminants of East Africa. Br. Mus. nat. Hist., 
London. Fossil Mammals of Africa, 15: iii + 50 pp., 18 figs. 

Younea, C. 1937. Ona Miocene fauna from Shantung. Bull. geol. Soc. China, Peking, 17 : 
209-238, 17 figs, pls 1-3. 


W. R. HamiLton, Ph.D., 

Department of Palaeontology, 

BriTisH Museum (NATURAL History), 
CROMWELL Roap, LonDoN SW7 5BD 


IIL ANAS i 


Fic. 1. Dorcatherium libiensis sp. nov. Right mandible, occlusal aspect. Holotype 


(M.26684) 1-6 approx. 
Fic. 2. Canthumeryx sirtensis gen. et. sp. nov. Right M; and D4; occlusal aspect. 


(M.26683) 1-6 approx. 
Fic. 3. Canthumeryx sirtensis gen. et sp. nov. Right Mj; lingual aspect. (M.26683) 


x 1-4 approx. 
Fic. 4. Canthumeryx sirtensis gen. et sp. nov. Right mandible; occlusal aspect. 


Holotype (M.26682). 
Fic. 5. Canthumeryx sirtensis gen. et sp. nov. Right P4 and Ps; occlusal aspect. 


(M. 26683) 1-5 approx. 
Fic. 6. Palaeomerycidae indet. Ossicones; anterior aspect. (M.26690). 


Bull. Br. Mus. nat. Hist. (Geol.) 21, 3 PLATE 1 


PIgA iE 2 


Zarafa zelteni gen. et sp. nov. Skull; lateral aspect. Holotype (M.26670). 


Bull. 


Bry. Mus. nat. Hist. (Geol.) 21, 3 


PIL, 


ATE 


iS) 


PLATE 3 


Zarafa zelteni gen. et sp. noy. Skull; dorsal aspect. Holotype (M.26670). 


~- 


ol.) 21, 


se! 


(¢ 


nat. Hist. 


Mus. 


Bull. Br. 


PLATE 4 
Fic. 1. Zarafa zelteni gen. et sp. nov. Supraoccipital region; posterior aspect. Holotype 
(M.26670) 1-2 approx. 
Fic. 2. Zarafa zelteni gen. et sp. nov. Basicranial region; ventral aspect. Holotype 
(M.26670)  -68 approx. 
Fic. 3. Zarafa zelteni gen. et sp. nov. Right mandible; lingual aspect. (M.26675) 
x +54 approx. 


fe) 
o 
a 
— 
ss 
n 
+s 
S 


Mus. 


Bull. By. 


Fic. 1. 
(M.26672) 
FIG. 2. 
approx. 
Fia. 3. 
approx. 
FIG. 4. 
approx. 
Fic. 5. 
approx. 


Zarafa zelteni gen. 


1-7 approx. 


Zarafa zelteni gen. 


Zarafa zelteni gen. 


Zarafa zelteni gen. 


Zarafa xelteni gen. 


PLATE 5 


et sp. nov. 
et sp. nov. 
et sp. nov. 
et sp. nov. 


et sp. nov. 


Left upper, juvenile dentition; occlusal aspect. 


Right Me; occlusal aspect. 
Right Mg; lingual aspect. 
Right M3; occlusal aspect. 


Right Ms; occlusal aspect. 


(M.26677) 
(M.26677) 
(M.26675) 


(M.26676) 


Bull. Br. Mus. nat. Hist. (Geol.) 21, 3 PLATE 5 


F* 


PLATE 6 


Fic. 1. Zarafa zelteni gen.et sp.nov. Right upper dentition; occlusal aspect. (M.26671) 
1-7 approx. 

Fic. 2. Zarafa zelteni gen. et sp. nov. Right upper dentition; labial aspect. (M.26671) 
1-7 approx. 


Bull. By. Mus, nat. Hist. (Geol.) 21, 3 PAGE 6 


PLATE 7 


Prolibytherium magnieri Arambourg 1961. Skull and ossicones, ventral aspect. (M.21901). 


Bull. By. Mus. nat. Hist. (Geol.) 21, 3 PAC 7 


PIL INAS, 


Prolibytherium magnieri Arambourg 1961. Left maxilla and upper dentition; lateral 
aspect. (M.21901) 1-4 approx. 


Bull. Br. Mus. nat. Hist. (Geol.) 21, 3 PLATE 8 


PLATE 9 


Prolibytherium magnieri Arambourg 1961. Left upper dentition and palate. (M.21901) 
1-4 approx. 


Bull. Br. Mus. nat. Hist. (Geol.) 21, 3 PLATE 9g 


PLATE to 


Fic. 1. Prolibytherium magnieri Arambourg 1961. Basicranial region; ventral aspect. 
(M.21901) 0-8 approx. 

Fic. 2. Prolibytherium magnieri Arambourg 1961. Occipital region; posterior aspect. 
(M.21901) 0-6 approx. 

Fic. 3. Prolibytherium magnieri Arambourg 1961. Left M3; occlusalaspect. (M.2668r) 
<2 approx. 

Fic. 4. Prolibytherium magnieri Arambourg 1961. Left M3; lingual aspect. (M.2668r) 
x2 approx. 


Bull. Br. Mus. nat. Hist. (Geol.) 21, 3 PLATE to 


PLATE 11 


Fic. 1. Prolibytherium magnieri Arambourg 1961. Right mandible; occlusal aspect. 
(M.21899) 1 approx. 

Fic. 2. Prolibytherium magnieri Arambourg 1961. Right mandible; labial aspect. 
(M.21899) XI approx. 

Fic. 3. Prolibytherium magnieri Arambourg 1961. Right petrosal; ventro-lateral 
aspect. (M.21g01) 1-7 approx. 

Fic. 4. Prolibytherium magnieri Arambourg 1961. Right petrosal; dorso-medial aspect. 
(M.21901) 2 approx. 


Bull. By. Mus. nat. Hist. (Geol.) 21, 3 PLATE t1 


PAE TANASE mere, 


hic. 1. Prolibytherium magnieri Arambourg 1961. 


aspect. (M.26678) 1-3 approx. 
Fic. 2. Prolibytherium magnieri Arambourg 1961. 
(M.26678) 1-3 approx. 


Endocranial cast; right lateral 


Endocranial cast; dorsal aspect. 


nat. Hist. (Geol.) 21, 3 


PLATE 13 


Fic. 1. Left. Protragocerus sp. Horncore; left lateral aspect. (M.26687). Right. 
Eotragus sp. Horncore; right lateral aspect. (M.26688). 

Fic. 2. Gazella sp. Left mandible; occlusal aspect. (M.26685) 0-78 approx. 

Fic. 3. Gazella sp. Left mandible; lingual aspect. (M.26685) 0-78 approx. 

Fic. 4. Gelocus whitworthi sp. nov. Left Mz and M3; occlusal aspect. Holotype (K.Sgr. 
305.1949) 3:3 approx. 

Fic. 5. Gelocus whitworthi sp. nov. Left Mz and M3; lingual aspect. Holotype (K.Sgr. 
305.1949) 3:3 approx. 


Bull. By. Mus. nat. Hist. (Geol.) 21, 3 PIL NANI, 113} 


PLATE 14 


Fic. 1. Propalaeoryx nyanzae Whitworth 1958. Right Mz and M3; occlusal aspect. 
(K.774.52) 2:9 approx. 

Fic. 2. Propalaeoryx nyzanzae Whitworth 1958. Left M! and P*4; occlusal aspect. 
(I<.Mt.67.51) 2-9 approx. 

Fic. 3. Propalaeoryx nyzanzae Whitworth 1958. Left M! and P#4; lingual aspect. 
(K.Mt.67.51) 2-9 approx. 


Bull. By. Mus. nat. Hist. (Geol.) 21, 3 PLATE 14 


‘ 
: ol 


A LIST OF SUPPLEMENTS 
TO THE GEOLOGICAL SERIES 
OF THE BULLETIN OF 
THE BRITISH MUSEUM (NATURAL HISTORY) 


Pp. 213; 30 Plates; 2 Text-figures. 1965. 
. Ex-Nacear, Z. R. Stratigraphy and Planktonic Foraminifera of the Upper — 
Cretaceous—Lower Tertiary Succession in the Esna-Idfu Region, Nile Valley 
Egypt, U.A.R. Pp. 291; 23 Plates; 18 Text-figures. 1966. f10. me. 
. Davey, R. J., Downtz, C., SARGEANT, W. A. S. & Pare G. L. Studies o or g x 


figures. 1966. £7. . 
. APPENDIX. Davey, R. J., DowniE, C., SARGEANT, W. A. S. & WILLIAMS, c. : 
Appendix to Studies on Mesozoic and Cainozoic Dinoflagellate Cysts. ‘Pp. 
1969. 8op. ° 
. Erziott, G. F. Permian to Palaeocene Calcareous Algae (Dasycladaceae) of th " 
Middle East. Pp. 111; 24 Plates; 17 Text-figures. 1968. {5.12}. “ 
. Ruopes, F. H. T., Austin, R. L. & Druce, E. C, British Avonian ( (Carboni ni- 
ferous) Conodont faunas. and their value in local and continental correlation. 
Pp. 315; 31 Plates; 92 Text-figures. 1969. {TII. * 
. Cuttps, A. Upper Jurassic Rhynchonellid Brachiopods from Northw [ 
Europe. Pp. 119; 12 Plates; 40 Text-figures. 1969. £4.75. ce 
. Goopy, P. C. The relationships of certain Upper Cretaceous Teleoae . 
special reference to the Myctophorids. Pp. 255; 102 Text-figures. 1969. {6. 
. OwEN, H. G. Middle Albian Stratigraphy in the Paris Basin. he 
3 Plates; 52 Text-figures. 1971. {6. 


from West Pakistan. Pp. 98; 42 Plates; 7 Text-figures. 1971. {£8. 


. oe 


BCG Printed in England by Staples Printers Limited at their Kettering, Northants establishment 


te WALKER 


roe te 


: BL : 
NATURAL HISTORY) 
Doct hema Vol. 21 No. 4 


ets 


i fang 
iN 


Ee Ar PINITIES"OF HALCYORNIS 
FROM THE LOWER EOCENE 


BY 
COLIN JAMES OLIVER HARRISON 
AND 
CYRIL ALEXANDER WALKER 


Pp. 151-169; 3 Plates, 9 Text-figures 


BULLETIN OF 
THE BRITISH MUSEUM (NATURAL HISTORY) 
GEOLOGY Worl 2 New 4 
LONDON : 1972 


THE BULLETIN OF THE BRITISH MUSEUM 
(NATURAL HISTORY), instituted im 1949, 1s 
issued in five series corresponding to the Departments 
of the Museum, and an Historical serves. 


Parts will appear at irregular intervals as they become 
veady. Volumes will contain about three or four 
hundred pages, and will not necessarily be completed 
within one calendar year. 


In 1965 a separate supplementary series of longer 
papers was instituted, numbered serially for each 
Depariment. 


This paper is Vol. 21, No. 4 of the Geological 
(Palaeontological) series. The abbreviated titles of 
periodicals cited follow those of the World List of 
Scientific Periodicals. 


World List abbreviation 
Bull. Br. Mus. nat. Hist. (Geol.) 


© Trustees of the British Museum (Natural History), 1972 


TRUSTEES OF 
THE BRITISH MUSEUM (NATURAL HISTORY) 


Issued 31 October, 1972 Price £1.55 


mie APFINITIES OF HALCYORNIS FROM THE 
POWER EOCENE 


By C. J. O. HARRISON & C. A. WALKER 


CONTENTS 
Page 
I. HusroricAL INTRODUCTION . . é : : 153 
II. DESCRIPTION AND STATE OF PRESERVATION . . : : 154 
IfI. COMPARISON WITH RECENT FORMS . 157 
IV. DETAILED COMPARISON WITH CORACIIFORM AND PICIFORM SPECIES 163 
V. POSSIBLE CHARACTERS OF HALCYORNIS ¢ : : ; 167 
VI. GENERAL CONCLUSIONS . ; : : 2 5 F : 167 
VII. SYSTEMATIC DESCRIPTION : : : : . . : 168 
VIII. ACKNOWLEDGEMENTS. F : ‘ : 3 . 3 169 
IX. REFERENCES. : : j 5 ; 3 ‘ : : 169 
SYNOPSIS 


Halcyornis toliapicus (Koenig) of the Lower Eocene, known from a single cranium, has been 
classified with the gulls (Koenig, 1825 and Lydekker, 1891) and the kingfishers (Owen, 1846). 
The specimen has now been fully prepared; it is redescribed here and its probable affinities 
re-appraised on the characters now apparent. 

A comparison with Recent forms indicates a general similarity to skulls of Coraciiformes and 
Piciformes. A more detailed examination of a range of species representing families within 
those two orders indicates that the greatest similarity is to the Coraciiformes, particularly to the 
rollers of the Coraciidae and Leptosomatidae. The characters of the fossil specimen do not 
appear to indicate stronger affinities with either one of those families, however, and it is therefore 
proposed that Halcyornis should be regarded as the type- (and only known) genus of a new 
family within the Coraciiformes. A diagnosis is given of the Halcyornithidae. 


I. HISTORICAL INTRODUCTION 


In the earlier part of the 19th century the cranial portion of a small bird skull was 
found in the London Clay, Ypresian (Lower Eocene) of the Isle of Sheppey, Kent, 
England. It was figured by Koenig (1825), who noted the general resemblance of 
the rounded cranium with its even, tapering temporal fossae to that of some of the 
smaller gulls (e.g. Larus canus or L. ridibundus) and therefore reconstructed it as a 
small gull, calling it Larus toliapicus. 

Owen examined the specimen, and noted (1846 : 554) the absence of the supra- 
orbital grooves which accommodate the lacrimal glands (grooves which are normally 
present in, and typical of, gulls and most other sea-birds). He compared the 
specimen with Recent material but may have used an incomplete collection. He 
noted the resemblance of the temporal fossae to those of the kingfisher, Alcedo atthis 
(although in the latter the fossae extend upwards until they almost meet in the mid- 
line) and, believing that it was probably an early kingfisher, called it, ‘Halcyornis 
tohapicus. Bird probably of the family Halcyonidae’. The kingfisher family is 
now known as the Alcedinidae. 


154 AFFINITIES OF HALCYORNIS 


Lydekker (1891 : 183) considered the specimen to be a gull. He rejected Owen’s 
suggestion because the temporal fossae on the posterior part of the cranium were 
further apart than in the kingfisher; and also because of the narrowness of the inter- 
orbital bar formed by the frontal bones. He commented that, ‘the imperfection of 
the fronto-parietal region renders it difficult to be sure as to the presence of super- 
orbital grooves, but the appearance suggests their presence’. He associated with 
the skull the distal end of a left humerus (BMNH No. A 10) which he considered to 
be of larid origin. There appears to be no reason for associating the humerus with 
the cranium; the former has therefore been considered as a separate specimen and 
has not been dealt with in the present paper. 

We have compared Halcyornis with a range of Recent bird bones in the British 
Museum (Natural History). The most obvious character, and the one on which 
earlier identifications were based, is the presence of well-defined temporal fossae 
which occupy about two-thirds of the total width of the cranium. They are of 
fairly even shape, tapering posteriorly, with a slightly concave posterior margin. 
The search for similar Recent species showing this type of posteriorly-rounded 
cranium with relatively simple temporal fossae produced a number of alternative 
possibilities, allowance having been made for a reasonable degree of variation. 
Specimens with some similarity were found in the Procellariidae (Procellariiformes), 
Fregatidae (Pelecaniformes), Rhinochetidae (Gruiformes), Laridae (Charadriiformes), 
Cuculidae (Cuculiformes), Alcedinidae, Momotidae, Meropidae, Coraciidae, 
Upupidae, Leptosomatidae (Coraciiformes), Galbulidae, Bucconidae, Capitonidae, 
and Ramphastidae (Piciformes). So many families possess this type of skull that 
it is obviously an unsatisfactory character from the taxonomic point of view, but 
nevertheless provides an initial limited list of potentially related families 


Il. DESCRIPTION AND STATE OF PRESERVATION 


It was necessary to consider the other characters of the specimen, which was 
further prepared for this purpose, making some of the interorbital features more 
apparent. 

The specimen consists of the posterior portion of a cranium, imperfect in all its 
aspects. The roof has been broken away to show part of the endocranial cast and 
the anterior region is broken off about half-way along the frontals. The interorbital 
bar is narrow; the orbital rim is apparently undamaged, with no evidence of any 
superorbital grooves. There isa fairly large, well-marked temporal fossa the margin 
of which arises anteriorly at the junction between the postorbital processes and the 
orbital rim, runs obliquely backwards towards the mid-line, and then curves round 
to pass outwards along the dorsal border of the occiput. 

In lateral view the skull shows a cranium that is not particularly inflated or 
rounded, and the thick interorbital septum is perforated only by a single foramen for 
the optic nerve. This foramen is situated at the postero-ventral corner and is rather 
small. The orbital rim is raised slightly above the plane of the skull roof. The 
postorbital processes are broken on both sides, but would have been blade-like, with 


ENGLISH LOWER EOCENE 155 


narrow edges directed laterally. The temporal fossa forms, in this aspect, a well- 
marked groove between the postorbital process and the tympanic cavity. 

The palatal surface is eroded and much of the detail on the basiparasphenoid 
region has been lost. The rostroparasphenoid is thick and the alaparasphenoids 
swing out to form a wide angle with the former. The eustachian tubes are visible. 
There is a well-marked depression just posterior to the ridge which runs across and 
joins the two alaparasphenoids. Much of the basioccipital is broken, but the 
occipital condyle, although eroded, is still present and was small. The foramen 
magnum is directed posteroventrally, but its exact shape is impossible to determine. 
The profile of the occiput in this view is relatively flat with a slight swelling around 
the foramen magnum. 

The occiput is also damaged about the mid-line, but the shape is broadly crescentic, 
with a well-defined median ridge running down the parietals and supraoccipital to 
meet the dorsal rim of the foramen magnum in the mid-line. Either side of this 
ridge there is a well-marked groove, which probably indicates the border between 
the supraoccipital and opisthotic. There appear to have been no foramina in the 
supraoccipital. The temporal fossae are distinct from this angle and their posterior 
border forms a well-defined ridge along the upper edge of the occiput. The fossae 
do not, however approach the mid-line. 


Fic. 1. Halcyornis toliapicus. BM(NH) No. A 130. Cranium. Dorsal View, ~ 4. 


56 


Fic. 2. 


AFFINITIES OF HALCYORNIS 


Halcyornis toliapicus. BM(NH) No. A 130. Cranium. 


Lateral View, 


ENGLISH LOWER EOCENE 157 


MEASUREMENTS 
Maximum width across exoccipital region. ; 20°5 mm 
Minimum width between temporal fossae_.. : g mm 
Width between postorbitals : : 3 : 22 mm 
Width of interorbital bar. ' : é : 7 mm 
Minimum width of interorbital septum . : : 2.9 mia: 
Maximum depth of skull in orbital region. : 17 mm 
Maximum length of auditory meatus. ‘ : 9 mm 


Tic. 3. Halcyornis tohapicus. BM(NH) No. A 130. Cranium. Frontal View, x 4. 


Ill COMPARISON WITH RECENT FORMS 


From the description it is apparent that for determining relationships, characters 
might be used other than those used in the past. The most obvious of these relate 
EO: 

I. The upper edges of the orbit. 

2. The interorbital septum and foramen. 

3. The relative size and shape of the parasphenoid region. 


IES He 


APFINITIES OF BALCYORNIS 


Halcyornis tohiapicus. 


BM(NH) No. A 130. 


Cranium. 


Ventral View, X 4. 


Halcyornis toliapicus. 


BM(NH) No. A 130. 


Cranium. 


Posterior View, X 4 


ENGLISH LOWER EOCENE 159 


1. The edges of the orbit 

Lydekker’s views on the affinities of Halcyornis appear to have been strongly 
influenced by his opinion that the appearance suggested the presence of supraorbital 
grooves, subsequently destroyed. On birds which normally live on or by salt water, 


be - é 


H | 


Fic. 6. Diagrams of dorsal views of crania to show width of interorbital bridge. a, 
Alcedo; 8, Dacelo; c, Coccyzus; D, Halcyornis; ©, Larus: F, Puffinus; G, Rhynochetos; 
H, Fregata; 1, Coracias. 


160 AFFINITIES OF HALCYORNIS 


the supraorbital glands tend to become greatly enlarged and are housed in distinct 
grooves along the upper edges of the orbits (Text-fig. 6E, F). These glands, which 
assist salt-excretion, are much smaller in related fresh-water species. The grooves, 
where present, are on top of the skull and tend to occupy most of the upper edges of 
the orbits, reducing the thickness of the frontal bones in this region. They may be 
deepest towards the centre of their width, at times penetrating to the orbits below 
and forming a series of fenestrae, or they may give to the orbital edges an irregular or 
eroded appearance. A consistent feature is the distinct ridge of bone along the inner 
edge of each groove where the frontal bone is restored to its normal thickness. 

Since these ridges of bone are not apparent on Halcyornis it would be necessary, 
were it held that supraorbital grooves had been present, to assume that the entire 
bony shelf supporting the supraorbital glands had worn away completely, back to 
this ridge. Although the presence of the groove reduces the thickness of the frontal 
bone by removing part of its upper surface, it does not affect the underlying surface 
within the orbit which curves downwards away from the orbit edge in the normal 
manner; and therefore an orbit worn back to the inner edge of a supraorbital groove 
would show a considerable depth of worn or broken surface at the edge between the 
top of the skull and the inside of the orbit. The skull of Halcyornis does not; the 
upper edge of the orbit does not taper to a very narrow edge but shows an abrupt 
surface about one millimetre deep, suggesting that a small amount of wear may have 
occurred on a normal orbit lacking a supraorbital groove (Text-fig. 2A, B). Another 
character of the supraorbital grooves is that it tends to terminate rather abruptly 
posteriorly, with the inner ridge curving towards the orbit edge; thus if a groove were 
to wear away, the orbit edge would show a sharp discontinuity at this point. There 
is no such discontinuity in Halcyorms. 

The absence of a supraorbital groove suggests that the specimen is not related to 
the Procellariformes, Anseriformes or Charadriiformes (including Laridae). The 
Pelecaniformes (Text-fig. 6H) and Ciconiiformes, although in some cases associated 
with salt water, do not possess these supraorbital grooves. Since the groove is a 
relatively plastic and adaptable character in the families in which it now occurs, it 
might be argued that it could have been absent in some or all species in earlier 
epochs. It is known to be present in Miocene gulls but we have no definite proof 
that it was present earlier, and as an indication of relationship it can be assessed 
only in conjunction with other characters. 


2. The interorbital septum 

Halcyornis has a thick, unfenestrated interorbital septum (Text-fig. 3) with a 
single optic foramen in a low posterior position (Text-fig. 71). Most of the birds 
discussed in this paper have marked and often extensive interorbital fenestrae 
(Text-fig. 7); these include the Procellariiformes, Pelecaniformes, Ciconiiformes and 
Charadriiformes. In the skimmers (Rhynchops spp., Charadriiformes) a highly 
specialized method of feeding (Zusi, 1962) has necessitated extra strengthening of 
the skull, including the development of a thick, solid interorbital septum; the latter, 
however, is pierced by the optic foramen in a high position (Text-fig. 7C) and there 
are small paired fenestrae opening into the cranial cavity just above this. Inter- 


ENGLISH LOWER EOCENE 161 


orbital fenestrae are also present in the Rhinochetidae, Cuculidae, and Alcedinidae. 
On the other hand the coraciiform and piciform families listed earlier generally show 
a solid interorbital septum with a low posterior optic foramen like that of Halcyornis ; 
the only exceptions are the Upupidae with a pair of fenestrae opening into the cranial 
cavity from the upper orbits and the Momotidae with a tiny variable “‘relict’’ 
foramen in the mid-septum. On the basis of this character there is a strong case 
for linking Halcyornis with the Coraciiformes and Piciformes, although the example 
of Rhynchops indicates that exceptional circumstances could lead to some adaptive 
variation in the fenestration of the septum. 


Fic. 7. Diagrams to show interorbital septa and position and size of interorbital foramina. 
A, Fregata; B, Puffinus; c, Rhynchops; v, Dacelo; ©, Merops; ¥, Upupa; G, Leptosomus; 
H, Eurystomus; 1, Halcyornis. 


162 AFFINITIES OF HALCYORNIS 


Another character in which Halcyornis resembles species of the Coraciiformes and 
Piciformes is the shape of the angle formed by the interorbital septum and the 
underside of the interorbital bridge section of the frontals (Text-fig. 8). On most of 
the Recent species examined the interorbital bridge is relatively thin and the septum 
extends well up towards the orbit where it meets the underside of the frontal at a 
sharp angle. In Halcyornis the interorbital bridge is much thicker towards the 
mid-line and tapers down more gradually, making an obvious junction with the 
septum at about a third of the distance between the top of the bridge and the base of 
the septum (Text-figs 2A, 2B, 3). This is less obvious anteriorly where the bone 
narrows, but can be clearly seen in lateral view as a discontinuity crossing the inner 
orbit. This heavier tapering interorbital bridge is apparent on skulls of Momotus 
(Coraciiformes) and Megalaima, Selenidera and Monasa (Piciformes). Eurystomus, 
Leptosomus and Merops (all Coraciiformes) show a similar low junction between 
septum and frontal inside the orbit; in these genera, however, there is a mid-line 
hollow on the top of the skull and the frontal is concave in cross-section, so that the 
apparently lower position of the junction is due to a general ventral displacement 
and cannot be regarded as an homologous development. 


3. The parasphenord region 

We have followed Jollie (1957) in regarding the externally visible ventral bones of 
the hind-skull as parasphenoid rather than sphenoid. The basiparasphenoid of 
Halcyornis is transversely elongated and roughly oblong, with a slight lateral taper 
(Text-fig. 4, Pls 1B, 3E). It is rather flat and this may have been emphasized by 
pressure and slight erosion. Anteriorly it terminates in a distinct edge where it 
abuts on the alaparasphenoids. The rostroparasphenoid is thick and has a small 
but distinct ventral prominence near the posterior end. The most conspicuous 
feature on each side is the alaparasphenoid, directed strongly laterally at the hind 
end of the rostroparasphenoid to form a prominent bulging ridge at the back of the 
base ot the orbit, curving upwards to meet the orbitosphenoid. The lateral ends of 
both alaparasphenoids and the basiparasphenoids are broken away. 

In the Procellariformes (Pl. 3C) the basiparasphenoid tapers markedly towards the 
front and there is a narrow gap between it and the ventrally projecting edge of what 
appears to be the orbitosphenoid. The Pelicaniformes show a tapering basipara- 
sphenoid which becomes distinctly wedge-shaped in some forms, and in Fregata 
(Pl. 3B) there is again a gap between the basiparasphenoid and orbitosphenoid. In 
the Charadriiformes (Pl. 3D, F) this anterior taper is again apparent on the basi- 
parasphenoid, while the alaparasphenoid is more prominent than in the previous 
taxa but slants away weakly to the orbital and otic region, least so in some small 
Larus species such as L. ridibundus. The Cuculiformes (Pl. 3L) show a wedge- 
shaped basiparasphenoid, narrow anteriorly in some species but broad in others, 
and the alaparasphenoid is poorly defined. 

In these characters, as in the previous ones, the greatest similarity to Halcyornis 
is shown by piciform and coraciiform birds. In most of these the basiparasphenoid 
is wide transversely, tending towards an oblong shape with little lateral taper; in the 
Capitonidae (Piciformes) and in the Coractidae (Pl. 3H) Leptosomatidae, and 


ENGLISH LOWER EOCENE 163 


Momotidae (Coraciiformes) it has a similar shape to the fossil, but in the Bucconidae 
(Pl. 31) and Galbulidae (Piciformes) and in the Alcedinidae (Pl. 3J) and Meropidae 
(Pl. 3G) (Coraciiformes) the distance between the orbits and the foramen magnum is 
shortened, making the basiparasphenoid narrower from front to back. 

In both orders many species have a pair of small prominences on the ventral 
surface of the basiparasphenoids. These are very variable, being almost absent, for 
instance, on Alcedo (Alcedinidae). In Halcyornis this bone shows a pair of small 
areas with dull surfaces suggesting abrasion or heavy pressure, corresponding in 
position to these prominences although one is a little displaced by fracture. 

The principal difference between the Piciformes and Coraciiformes lies in the 
development of the Alaparasphenoid. On the piciform skulls examined this 
element is barely apparent, although there is a small, poorly developed ridge on the 
skulls of the larger Megalaima species. In the Coraciiformes the alaparasphenoid 
shows some variation in development in the Meropidae, Leptosomatidae, and many 
of the Coraciidae it is well developed, as a distinct projecting ridge at the posterior 
basal edge of the orbit, the resemblance to Halcyornis being especially strong in the 
rollers Leptosomus, Eurystomus and Coracias. 

In both orders the rostroparasphenoid is relatively stout ; Merops (Meropidae) and 
Dacelo (Alcedinidae) show a ventral prominence near the posterior end which is 
like that on the fossil. 


Conclusions 

The characters of Halcyornis listed above afford no good reason for linking it with 
either the Laridae or the Charadriiformes. The only orders with which it appears to 
show any consistent affinities are the Piciformes and the Coraciiformes; insofar as 
the parasphenoid region is concerned it seems more like the Coraciiformes, in 
particular the Coraciidae and the Meropidae. 


IV. DETAILED COMPARISON WITH CORACIIFORM 
AND PICIFORM SPECIES 


The species within these two orders do not show uniform skull characters, for they 
have evolved differences in feeding habits and bill-shape and therefore exhibit 
varying degrees of divergence from a hypothetical ancestral form. Specimens of 
the following species were used in this comparison: 


CORACITFORMES 

Alcedinidae 
Dacelo novaeguineae 
Alcedo atthis 

Momotidae 
Momotus sp. 
Aspatha gularis 
Baryphthengus ruficapillus 

Meropidae 
Merops apiaster 


164 AFFINITIES OF HALCYORNIS 


Leptosomatidae 
Leptosomus discolor 
Coraciidae 
Atelorms pittoides 
Coracias garrulus 
Eurystomus glaucurus 
Upupidae 
Upupa epops 


PICIFORMES 
Galbulidae 
Galbula leucogastra 
Bucconidae 
Monasa morphoeus 
Capitonidae 
Megalaima virens 
M. haematocephala 
Ramphastidae 
Selenidera langsdor ffi 


1. Cranial shape 

The general roundness of the fossil cranium in lateral view (Text-fig. 2A, B) is 
similar to that of Monasa morphoeus, Megalaima haematocephala (Text-fig. 8B), 
Selentdera langsdorffi and the Momotidae species. Most of the others have a cranium 
extending further back and with a slight upward taper, apparently caused by a 
forward shift of the foramen magnum and a shortening of the basiparasphenoid area 
so that the occiput faces more ventrally. This shift of the foramen would seem to 
be linked with a more upright perching stance by the bird. In Leptosomus and 
Eurystomus this shift is accompanied by a shortening of the cranium but this appears 
to be compensated for by an increase in the height, the cranium bulging noticeably 
at the top. In Upupa there is no apparent shift but the cranium is generally 
enlarged and rounded. 


2. Lemporal fossae 

It has already been indicated that the size and shape of the temporal fossae (site 
of origin of the M. adductor mandibulae externus) varies considerably from species 
to species. The two examples of Megalaima demonstrate this. The fossae of the 
smaller species (M. haematocephala, Text-fig. 8B) are little larger than those of 
Halcyornis, but those of the larger bird (M. vivens, Text-fig. 8D) are considerably 
elongated and extend across to meet at the back of the skull. In the Coraciiformes 
small fossae similar in size to those of Halcyornis but differing a little in shape occur 
on the various Momotidae species (Text-fig. 8C). In Leptosomus they are also 
small, but on other species show a variable tendency to become elongated towards 
the mid-line, almost meeting in Atelornis pittordes and the Alcedinidae (Text-figs 6B, 
8F). The temporal fossae of Halcyornis extend well forwards anterodorsally, 


ENGLISH LOWER EOCENE 165 


approaching the orbit closely and reducing the spur above the postorbital process to 
a narrow ridge. A slight discontinuity in the floor of the fossae, adjacent to the 
process, seems to indicate a secondary area of muscle attachment, probably of the 
M. dermotemporalis, an accessory muscle of the neck used in head movements. 
This area is relatively poorly developed in most of the forms considered here but is 
rather more apparent in Megalaima haematocephala, Monasa morphoeus and Upupa 
epops, although very shallow in Upupa. The narrower ridge of the postorbital 
process in Leptosomus discolor and Selenidera langsdorffi appears to be due to an 


Fic. 8. Diagrams of left lateral posterior views of crania to show variation and extent of 
temporal fossae. a, Covacias; B, Megalaima haematocephala; c, Momotus; D, Megalaima 
vivens; E, Larus; F, Alcedo. 


166 AFFINITIES OF HALCYORNIS 


increase in the M. adductor mandibulae externus rather than M. dermotemporalis. 
The relatively small size of the M. dermotemporalis in the species which actively 
hunt live prey, and its development in species which tend to take insects from a solid 
substrate or to take fruit, suggests that the relatively plastic shape of the fossae is 
linked with the type of feeding behaviour. 


3. Interorbital bridge and dorsal groove 


Dorsally the cranium of Halcyornis tapers to a relatively narrow interorbital 
bridge formed by the frontals (Text-fig. 1), and there is a distinct groove along the 
mid-line (Text-fig. 3, Pl. 1A). The skull roof also bears a series of fine striae radiating 
from the edges of the orbits, mostly directed posteriorly (Text-fig. 1). 

Over the two orders as a whole the trend appears to be for the interorbital bridge 
to become gradually broader (Text-fig. 6). The bridge is fairly narrow on Aspatha 
gularis and Atelornis pittoides, but only in Blcedo atthis (Text-fig. 6A) does it approach 
the narrowness of Halcyornis. Milne-Edwards and Grandidier’s (1876) plate of the 
skull of the Madagascan Roller, Bractypteracias leptosomus (Coraciidae), shows that 
this too had a narrow interorbital bridge. In the Alcedinidae the width of the 
bridge varies (Text-fig. 6A, B), the narrow bridge apparently correlated with a 
slender bill. The dorsal groove is apparent in species of Momotidae, Alcedinidae, 
Upupidae, Leptosomidae and most Coraciidae; poorly defined in Atelornis pittoides, 
Monasa morphoeus and Merops apiaster; virtually absent in the Ramphastidae; 


E F e H 


Fic. 9. Diagrams of the left external auditory meatus. a, Halcyornis; B, Eurystomus 
glaucurus; c, Leptosomus discoloy; D, Covacias garrulus; E, Dacelo novaeguineae; F, 
Megalaima vivens; G, Monasa morphoeus; a, Momotus martit; approx. } nat. size. 


ENGLISH LOWER EOCENE 167 


and replaced by a ridge in the Galbulidae and Capitonidae. The striae, which we 
suspect may vary with age and the degree of ossification, are more or less apparent 
in most of these species. 


4. Occipital region 


The fossil shows a very definite curved occiput of fairly even width (Pl. 1C). The 
lateral ends (formed by the exoccipitals) terminate in a narrow ridge which is also 
the posterior edge of the auditory meatus, and this ridge curves abruptly at the top 
to form a small arch almost at the point where the ridge of the upper edge of the 
occiput terminates. 

Most of the skulls examined show an occiput similar to that of Halcyornis, but its 
degree of curvature varies from one species to another. On most of them the ridge 
of the upper edge of the occiput terminates laterally in a triangular-shaped surface 
which slopes down towards the meatus, the upper arch of which is less acute than in 
Halcyornis, lower and more anterior in relation to the exoccipitals. The rollers 
Eurystomus glaucurus and Coracias garrulus (Text-fig. 8A), however, are much more 
like Halcyornis. Firstly, the occiput is very similar in shape and relative size; 
secondly, in F. glaucurus and to some extent in C. garrulus the triangular surface is 
very small and the upper edge of the meatus terminates in a small acute arch, near 
the end of the occipital ridge, very similar to that of Halcyornis (Text-fig. 9). In the 
latter some allowance must be made for probable erosion of these surfaces. 


V. POSSIBLE CHARACTERS OF HALCYORNIS 


When a fossil bird is known only from an incomplete skull, any ideas concerning 
its appearance or habits must necessarily be highly conjectural. It is, however, 
possible to make a few intelligent guesses by extrapolation from Recent species. 
The size of the fossil skull, compared with those of other birds, suggests that 
Halcyornis was probably about the size of a medium-sized thrush (Turdus sp.). The 
position of the foramen magnum suggests that the bird did not have the very 
upright posture of the present-day rollers (Coraciidae) and kingfishers (Alecinindae) 
but probably adopted a more horizontal body posture on a perch or on the ground, 
like that of the smaller barbets (Capitonidae). The narrow bridge between the 
orbits suggests that the bill was probably slender and more like a typical kingfisher’s 
than a roller’s. Most birds of this type which catch living food by rapid and 
vigorous movements have temporal fossae extending well back around the skull; 
but the temporal fossae of Halcyornts are fairly small and rounded, suggesting that 
this species may have taken food, probably small creatures or fruit, from the sub- 
strate or from the surfaces of vegetation rather than by seizing it rapidly in the air. 


VI. GENERAL CONCLUSIONS 


From an examination of affinities within the higher taxa it is apparent that 
Halcyornis toliapicus has been wrongly assigned to the Laridae and that its true 
affinities seem to lie with the Coraciiformes and Piciformes, more specifically with 
the former. The subsequent comparison with families within those two orders 


168 AFFINITIES OF HALCYORNIS 


appears to confirm that conclusion and to reinforce the view that the closest 
affinities are with the Coraciidae. The similarities are not sufficient, however, to 
justify referring it to that family, and it appears to show the characters of several 
families, and also exhibits its own peculiarities and combination of characters. 
Hitherto Coraciiformes have not been described from the Lower Eocene, but the 
momotid Uzintornis! has been described from the middle Eocene of Wyoming, the 
bucerotid Gezsleroceros from the Middle Eocene of Germany, the coraciid Geran- 
opterus from the Upper Eocene of France, and the alcedinid Protornis from the Upper 
Eocene of Switzerland. Halcyornis, because of its earlier origin, might be a repre- 
sentative of a group ancestral to more than one of the Recent families. As a matter 
of taxonomic convenience it seems best for the present to treat Halcyornis as the 
unique representative of a new family of the Coraciiformes, systematically not far 
removed from the Coraciidae: the Halcyornithidae. 


VI. SYSTEMATIC DESCRIPTION 
Order CORACIIFORMES 
Family HALCYORNITHIDAE noy. 


FAMILY DIAGNOSIS: Cranium not particularly inflated or rounded. Interorbital 
bar narrow and deep. Postorbital process small and narrow. Temporal fossae 
tapering posteriorly, occupying about two-thirds of total width of cranium, slightly 
curved where they border the edge of exoccipital region. Occiput semi-lunar with 
well-defined median ridge on parietals. Interorbital septum thick, with single 
optic foramen in low position. Wide angle between alaparasphenoids and rostro- 
parasphenoid, latter thick. 


Genus HALCYORNIS Owen, 1846 
DracGnosis: The only genus of its family. 


TYPE SPECIES: Halcyornis toliapicus (Koenig). 


Halcyornis toliapicus (Koenig, 1825) 
(Pls 1-3; Text-figs 1-9) 


1825 Larus toliapicus Koenig, pl. 16, fig. 193. 
1846 Halcyornis toliapicus (Koenig): Owen: 554. 


Dracnosis: The only species of the genus. 
Ho.otyreE: Imperfect cranium in Brit. Mus. (Nat. Hist.) No. A 130. 


LocaLITy AND HORIZON: London Clay (Ypresian), Lower Eocene of Sheppey, 
Kent, England. 


1According to Dr. J. Cracraft (pers. comm.), Uintornis is not a motmot. 


ENGLISH LOWER EOCENE 169 


Vill. ACKNOWLEDGEMENTS 


We wish to thank Dr. A. J. Charig and Dr. J. Cracraft for criticizing the manu- 
script; Mrs. T. E. D. Brendell for making the detailed line drawings; Mr. F. Howie 
for preparing the specimen and Mr. T. W. Parmenter for taking the photographs. 


IX. REFERENCES 


Jotyig, N. T. 1957. The head skeleton of the chicken and remarks on the anatomy of this 
region in other birds. J. Morph., Philadelphia, 100 : 389-436. 26 figs. 

Koenic, E. 1825. Icones fossilium sectiles. 44 pp. 19 pls. London. 

LYDEKKER, R. 1891. Catalogue of the fossil birds in the British Museum (Natural History). 
XII-368 pp. 75 figs. London. 

Mitne-Epwarps, A. & GRANDIDIER, A. 1876. Histoive physique, naturelle et politique de 
Madagascar. 13, Histoive naturelle des oiseaux. tome 2, Atlas 1. 87 pls, 236 figs. Paris. 

OweEN, R. 1846. A history of British fossil mammals and bivds. XLVI-560 pp. London. 

Zusi, R. L. 1962. Structural adaptations in the head and neck in the Black Skimmer. 
Publ. Nuttall Orn. Cl. 3, 101 pp. Cambridge, Mass. 


C. J. O. Harrison, Ph.D. 
Department of Zoology, 
Sub-depariment of Ornithology, 
ZooLocicaL Museum, 

TRING, 

HERTs. 


C. A. WALKER, 

Department of Palaeontology 

British Museum (Natural History) 
CROMWELL Roap, 

Lonpon, SW7 5BD 


TINA, a 


Halcyornis toliapicus BM(NH) No. A 130. 
Stereo views of cranium, X 2. 
A, dorsal; B, ventral; c, posterior. 


Bull. Bry. Mus. nat. Hist. (Geol.) 21, 4 PEATE 1 


PA Ee 2 


Halcyornis toliapicus BM(NH) No. A 130. 
Stereo views of cranium, 2. 
A, right lateral; B, left lateral; c, frontal. 


Bull. Br. Mus. nat. Hist. (Geol.) 21, 4 IIL ANTES, 2 


PLATE 3 


Ventral views of bird crania to show variations in basisphenoid elements. 


A, Rhynochetos jubatus 
B, Fregata ariel 

c, Puffinus diomedia 

D, Larus argentatus 

E, Halcyornis 

F, Rhynchops niger 

G, Merops apiaster 

H, Coracias garrulus 

1, Monasa morphoeus 
J, Dacelo novaeguineae 
K, Upupa epops 

L, Coccyzus erythropthalmus 
various magnifications 


Bull Br. Mus. nat. Hist. (Geol.) 21, 4 PLATE 3 


rY/ td Me cy 


" 


OF ii 
= , | we 


A LIST OF SUPPLEMENTS 
TO THE GEOLOGICAL SERIES 
OF THE BULLETIN OF 
THE BRITISH MUSEUM (NATURAL HISTORY) 


Pp. 213; 30 Plates; 2 fae oe (6. 
. Er-Nacear, Z. R. Stratigraphy and Planktonic Foraminifera of the 


Royse U.A-R.. Pp. 291; 23 Plates; 18 Text-figures. Sry £10. 

. Davey, R. J., DowniE, C., SARGEANT, W. A. S. & Wittiams, G.L. St 
Mesozoic and Cainozoic a eect Cysts. be 248; 28 he eees é 
figures. 1966. £7. 


Appendix to Studies on 1 Mesozoic and Cainozoic = Dinofagllate cysts. 
1969. 80p. ee 
. Exuiort, G. F. Permian to Palaeocene Calcaruote Algae (Dacycdadaceaen a 
Middle East. Pp. rrr; 24 Plates; 17 Text-figures. 1968. £5.12}. nage 
. Ruoves, F. H. T,, Austin, R. L. & Druce, E. C. British Avonian ( 
ferous) Conodont faunas, and their value in local and continental cor 
Pp. 315; 31 Plates; 92 Text-figures. 196g. {11 : 
. Cuitps, A. Upper Jurassic Rhynchonellid Brachiopods from Nort 
Europe. Pp. 119; 12 Plates; 40 Text-figures. 1969. £4.75. 
. Goopy, P. C. The relationships of certain Upper Cretaceous Tele 
special reference to the Myctophorids. Pp. 255; 102 Text-figures. 1969 
. Owen, H. G. Middle Albian Stratigraphy in the ed Basin. e 
3 Plates; 52 Text-figures. 1971. £6. e 
. Sippigul, Q. A. Early Tertiary Ostracoda of the family Teach 
from West Pakistan. Pp. 98; 42 Plates; 7 Text-figures. 1971. {£ 


ablle 


BEE #s: Printed in England by Staples Printers Limited at their Kettering, Northants, establishment 


‘U. GITMEZ 


DINOFLAGELLATE CYSTS AND ACRITARCHS 
FROM THE KIMMERIDGIAN (UPPER JURASSIC) 
OF ENGLAND, SCOTLAND AND FRANCE 


~~ y ~» 


anor te | 


FON 
i) 


A> 3 
(ae 


Lar URAL Wy 


BY 
GULDEN USMAN GITMEZ 
Hacettepe University, Ankara, Turkey 
AND 


WILLIAM ANTONY S. SARJEANT 


University of Saskatchewan, 
Saskatoon, Canada 


Pp. 171-257; 17 Plates; 27 Text-figures; 6 Tables 


BULLETIN OF 
THE BRITISH MUSEUM (NATURAL HISTORY) 
GEOLOGY Wolhen Now's 
LONDON : 1972 


THE BULLETIN OF THE BRITISH MUSEUM 
(NATURAL HISTORY), instituted in 1949, 1s 
issued in five series corresponding to the Departments 
of the Museum, and an Historical series. 

Parts will appear at irregular intervals as they 
become ready. Volumes will contain about three or 
four hundred pages, and will not necessarily be 
completed within one calendar year. 

In 1965 a separate supplementary series of longer 
papers was instituted, numbered serially for each 
Department. 

This paper is Vol. 21, No. 5 of the Geological 
(Palaeontological) series. The abbreviated titles of 
periodicals cited follow those of the World List of 
Scientific Periodicals, 


World List abbreviation 
Bull. Br. Mus. nat. Hist. (Geol.) 


© Trustees of the British Museum (Natural History), 1972 


TRUSTEES OF 
THE BRITISH MUSEUM (NATURAL HISTORY) 


Issued 1 November 1972 Price £4.65 


DINOPLAGELLATE CYSTS AND ACRITARCHS 
FROM THE KIMMERIDGIAN (UPPER JURASSIC) 
OF ENGLAND, SCOTLAND AND FRANCE 


By G. U. Gitmez & W. A. S. Sarjeant 


CONTENTS 
Page 
I. INTRODUCTION ‘ : : 5 9 : 175 
II. LocatTioN AND DESCRIPTION OF SAMPLES . b : . ; 176 
1. Dorset (South coast) . é : : F : : 176 
2. Oxfordshire c : : : : : c c 180 
3. Cambridgeshire . ‘ : F : j : . 180 
4. Warlingham, Surrey. ; A : : : : 180 
5. Isle of Skye (Staffin Bay) . : . : 6 181 
6. Eathie Haven (South of @ascee ; : ‘ : 181 
7. The Boulonnais . : : : : : : : 181 
8. Normandy . é ; i 2 : : : 182 
9g. Le Havre, Seine Eeieceace : > : 4 : : 183 
10, Lorraine. 4 : : : 3 184 
11. Mont Crussol (Rhéne vale) : . é : 184 
12. The Jura Mountains (Southern French ies) ‘ c ; 184 
III. SystTEMATIC SECTION 0 : 5 5 185 
Cyst-Family Fromeaceae Sige & eae : : : 185 
Genus Chytroeisphaeridia Sarjeant . : C : 185 
C. chytroeides Sarjeant . : : 6 : 185 
C. mantelli sp. nov. : : : ; ‘ 186 
C. pococki Sarjeant c : : : : 187 
Genus Fvomea Cookson & Eisenack . : : . 188 
F. warlinghamensis sp.nov. . ‘ : : 188 
Genus Tenua Eisenack emend. Sarjeant . > 5 189 
T. capitata (Cookson & ee) : : : 189 
T. echinata sp. nov. ‘ : ‘ 6 190 
T.sp. . : 2 190 
Cyst-Family Gorn relreyaeeae Sotennt & Deaae ; : 191 
Genus Cyryptarchaeodinium Deflandre emend. Gitmez . 191 
C. calcavatum Deflandre 5 5 4 3 IOI 
C. cf. calcavatum Deflandre . : ‘ 192 
Genus Gonyaulacysta Deflandre emend. Sarena : 193 
G. cauda sp. nov. . é : : : 193 
G. cf. giusepper Morteanot : : ¢ : 194 
G. globata sp. nov. : 6 : : . 195 
G. longicornis (Downie) : : F : 197 
G. cf. mamillifera (Deflandre) ‘ : ; 199 
G. nuciformis (Deflandre) : 5 ; ; 200 
G. perforans (Cookson & Eisenack) . : ; 202 
G. systvemmatos sp. nov. : : : : 204 
G. sp. A. : : c : : ° : 205 


174 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


Genus 


Genus 


Cyst-Family 


Genus 


Genus 


Genus 


Cyst-Family 
Genus 


Genus 


Cyst-Family 


DADNDHDAD 
wn 

OS OOK 

OB Ob 


Leptodinium Klement Suen’, Sarjeant 

L. acevas (Eisenack) 

L. amabilis (Deflandre) . 

L. cf. cvassinervum (Deflandre) 

ESD: 

Occisucysta Glas 

O. evitti (Dodekova) 

O. monoheuriskos sp. nov. 

Microdiniaceae Eisenack emend. Seeeant ad 
Downie 

Dictyopyxis Coakean & Beemer 

D. aveolata Cookson & Eisenack 

D. cf. reticulata (Valensi) 

Meiourogonyaulax Sarjeant 

M. staffinensis Gitmez 1970 

M. dicryptos sp. nov. 

M. pila sp. nov. 

M. sp. : 

Egmontodinium en nov. 

E. polyplacophorum sp. nov. 

Pareodiniaceae Gocht emend. Great & Downie 

A pteodinium Eisenack ¢ 

A. cf. maculatum Eisenack & Cankeon 

Imbatodinium Vozzhennikova 

I. antennatum sp. nov. 

I. cf. villosum erate 

Uncertain 


Proximate cyst sp. indet. 


Cyst-Family 
Genus 


Cyst-Family 


Genus 


Genus 

Genus 
Cyst-Family 

Genus 
Cyst-Family 


Genus 


Adnatosphaeridiaceae Seu & oer 

Adnatosphaeridium Williams & Downie 

A. paucispinum (Klement) : 

Hystrichosphaeridiaceae Evitt emend. Serene 
and Downie 

Cleistosphaevridium heme Dae. Gaeicant aud 
Williams : . 

Caspar 

Olccspiaeridaan Dewey & wv allems 

O. pulcherrimum (Deflandre & Cookson) 

Systematophora Klement 4 

S. ovata sp. nov. 

Uncertain 

Stephanelytron eae en 

S. vedcliffense Sarjeant 

S. cf. vedcliffense Sarjeant 

Endoscriniaceae Vozzhennikova saenil cane 
& Downie 

Endoscrinium (idement), 


206 
207 
208 
209 
211 
212 
213 
215 
215 
216 
218 
219 
220 
220 
221 


223 
223 
228 
224 
224 
224 
225 
226 
227 
228 
229 
231 
231 
231 
232 
232 
233 
233 
233 
234 
234 
234 


235 


235 
235 
235 
235 
237 
237 
237 
237 
237 
238 


239 
239 


FROM ENGLAND, SCOTLAND AND FRANCE 175 


Spa : : : 239 
Cyst-Family Hexagoniferaceae Sanjeant & Dawe : : 240 
Genus Hewxagonifera Cookson & Eisenack . 6 : 240 
H. jurassica sp.nov. . : . : : 240 

Cyst-Family Muderongiaceae Neale & Sarjeant emend. 
Sarjeant and Downie . d : : 241 
Genus Muderongia Cookson & Beedle 5 5 9 241 
M. simplex Alberti , 241 

Cyst-Family Nelsoniellaceae Eisenack emend. Sarjeant and 
Downie . : : : : 242 
Genus Scriniodinium ilemedee ; 6 6 2 242 
S. bicuneatum (Deflandre) : : é 5 242 
S. dictyotum Cookson & Eisenack . : 6 243 
S.sp. . - : : : 3 o 244 
Genus Sivmiodinium Alberti c : ; : é 245 
S. grossi Alberti. : é : : é 245 
Cavate cyst sp. indet. A. . : Q : : : 245 
Cavate cyst sp. indet. B.  . : : : c : 246 

Incertae sedis 

Group Acritarcha Evitt ; : 247 
Subgroup Acanthomorphitae Desusie Evict & Sonieeint : 247 
Genus Micrhystridium Deflandre emend. Sarjeant : 247 
M. vecuvvatum Valensi . c é 5 ; 247 
M.sp.. : 247 

Genus Solisphaeridium Sele. [easeaine & Pocock 
emend. Sarjeant : : : : 248 
S. claviculorum (Deflandre) i . 248 
Subgroup Netromorphitae Downie, Evitt & Sagiena é 249 
Organism A. . 249 
Subgroup Pteromorphitae acme, Evite & Sane . 249 
Genus Ptevospermopsis W. Wetzel . 4 c 3 249 
P. harti Sarjeant . : : : ; : 249 
Subgroup Uncertain . : : ; ; ‘ : 250 
Acritarch sp. indet. . : : 3 : : : 250 
IV. STRATIGRAPHICAL DISTRIBUTION CHARTS . : ; : F 250 
V. CONCLUSIONS : : : F ; : : P 6 250 
VI. ACKNOWLEDGEMENTS ‘ : 3 i ‘ j : : 252 
VII. REFERENCES . é : : : ; j , ; ‘ 253 


I. INTRODUCTION 


THIS paper contains an account of assemblages of organic-walled microplankton 
(dinoflagellates and acritarchs) from the Kimmeridgian of England, Scotland and 
France. Since an account has already been given of assemblages from the lowest 
Kimmeridgian, the Baylei Zone (Gitmez, 1970), attention is concentrated on the 
higher zones: however, additional records from the Baylei Zone are included and 
data respecting this zone is incorporated into the stratigraphical discussion. 

Many of the samples examined were collected by the second author (W.A.S.S.), 
with the help or under the guidance of a number of other geologists—in Dorset, 
from Dr. J. C. W. Cope (University of Wales, Swansea) ; in the French Jura and the 
Boulonnais, from Professor Derek V. Ager (then of Imperial College, London; now 
of the University of Wales, Swansea) ; in Normandy and Le Havre, from Dr, Michel 


176 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


Rioult (Université de Caen) ; in Lorraine, from M. Pierre L. Maubeuge; and in Skye, 
from Dr. Dennis Field (University of Nottingham). In addition, a series of samples 
from the Warlingham borehole of H.M. Geological Survey were made available for 
study, through the courtesy of the Director, Dr. F. W. Anderson and Dr. H. Ivimey- 
Cook; and samples from Cromarty and from Oxfordshire and Cambridgeshire were 
furnished respectively by Dr. W. D. Ian Rolfe (Hunterian Museum, University of 
Glasgow) and Dr. Robin I. Whatley (University of Wales, Aberystwyth). 

Preparation and preliminary study of the samples was done by the first author 
(G.U.G.), who also prepared most of the diagrams and photographs. The results 
were worked out jointly. It was found that many species were represented by 
insufficient individuals for satisfactory description; repreparation and further study 
of the samples were therefore to have been undertaken. This was precluded by the 
destruction by fire of the upper floor of the Geology building of the University of 
Nottingham in late March, 1970; all wet and dry samples and many microscope 
slides were lost and the research programme of the second author (W.A.S.S.) so 
seriously set back that further work on the Kimmeridgian cannot now be envisaged 
for some years to come. In consequence, it was considered that, since so little is 
known of the assemblages from these levels, the data currently available should be 
published forthwith. 

In many instances, samples examined did not yield assemblages; relatively pure 
limestones in particular proved unproductive, the bulk of the assemblages being 
obtained from clays or argillaceous limestones. Details are given here of the 
negative as well as of the positive results. 


II. LOCATION AND DESCRIPTION OF SAMPLES 


Since full stratigraphic details and sample numbers for the specimens from the 
Baylei Zone have already been given (Gitmez, 1970), these are summarized only 
briefly here. Location, position and specimen numbers for higher horizons are given 
in full. Nottingham University sample numbers are quoted, since these were 
employed in all notes made by the authors. [The samples themselves were all 
destroyed in the conflagration. | 

The history of the ammonite zonation proposed for the Kimmeridgian of England 
is outlined in Table 1. The zonation here adopted is based on that of Arkell (1956) 
and incorporates the modifications introduced by Cope (1967). 

(1) Dorset (South coast): 

The clay formation known as the Kimmeridge Clay represents long-continued 
deposition of muddy sediments. It is not a uniform deposit, for it includes several 
lithological types which may alternate in rapid succession; in addition to thick clays 
there are thin bands of mudstone and several prominent “‘stone-bands’’, formed by 
limestones of variable degrees of purity (see Arkell, 1933; Cope, 1967). 

The Kimmeridge Clay is well exposed on the Dorset coast, through faulting in 
Ringstead Bay and again near Osmington Mills which causes repetition of the 
succession. Around the type locality of Kimmeridge, the Kimmeridge Clay reaches 
its maximum thickness (495 m), but towards the west, in the Weymouth district, 
the thickness is nearly halved and inland it reduces to go m. 


177 


FROM ENGLAND, SCOTLAND AND FRANCE 


LOWER 


MIDDLE 


s}ug, 
soley 


topAeq eIuoZOIg 


NVIGUYOAXO 


toyAeq eru0z01g te[Aeq eruozoIg 


topAeq eIuojoIg 


snyeqorinus 
aoopow Ad eIuesery as0pourAd erIueseyy a90pourAd erIueseyy ss0pourAd erueseyy 
syiqeznur 
soprourydeajsoorpny sljiqejnu eruese yy SI]IqeyNU eruaser ST]IGe}NU eIUISeYT 
snxopnoe 
snueydeysoorny 
SUIQeIN]A,, 
SISUOIOPOISSINe stjIqezynuropnesd sijiIqeznuropnesd sijiIqeynuopnesd 
snueydeysoorny snueydojsoorpny snueydojsoorpny snueydoajsoorny 
suesojo BULISOACIS PISOAPID SUPISOALIS VISOAPID) 
(saprozyourydsozesita ) SOUOZ PISOAPIN) stdsei0q4S 
sopzeurzoog SPSIS PISOAPID SNTIT VISOARID) 
snynz10s 
(soprojourydsozesit A ) 
so}izeuroeg ‘dds sozruejdqns stsuoA9q} eo 
seprozourydsozesit A 
sisuoAo]} POT SISU9A OM YOS}EIUI 
(soprozoutydsoze 811 A ) $o}1}eSIT A 
sopzeurz00q sipueis soytuefdqns 
sniojIpou 
TuU0}soTpNny sisuoA9T} ROM soprozyourydsozesit, 
(seqTTe4TV) sezzeUIQOeq soyyuedqns 
snzeurjoed saqizeurz00q snzeurjoed sozizeur}00g snzeurzoed soqrzeurjOI9g snzeurjoed soqz1zeuI}I0g 
epunyzoL PIAC[ACG epunyzor eIAo[Aeg epunyzoL eCIAOQTAeG (epunjor etacjAeg) 
(snuetseyjed eraojaeg) 
soprorseyjed viAojardg soprorseyed eraojAeg soprorserjed eraocjaeg (soprotseyyed eraojAeg) 
NVIGNVILUOd 
£961 adog 10932 9S61 S761 br61-€ 161 gSgi—9Ser 
peyipour ‘9S6r [[ayxIV TexrtVv WOSIOAPO NT PIPyIes jeddo 


ULISPILOWUWITY 94} JO UOIJLOYISse[O [euOz 9Yy3 Jo AIO4STY OY, 


I ATAV] 


178 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


The samples studied were collected from two areas, the Isle of Purbeck and the 
Weymouth district (Text-fig. 1). Fourteen samples were examined from the Isle of 
Purbeck. (The colours are given according to the ““Rock Colour Chart”, produced 
by the Geological Society of America [1963] and based on the Munsell System.) 

Autissiodorensis Zone: 

I. KD 221—Shale containing shell fragments, medium grey in colour (N5), 
from c. 4 ft above Washing Ledge Stone Band, Kimmeridge (National Grid Reference: 
909791). 

2. KD 224—Clay containing shell fragments, medium dark grey in colour (N4), 
from 30 ft above Maple Ledge Stone Band, Kimmeridge. (National Grid Reference: 
909788.) [Very few microfossils were obtained from this sample. | 

3. KD 225—Clay containing shell fragments, medium dark grey in colour (N4), 
from immediately below the cementstone at the junction of the Autissiodorensis and 
Elegans Zones, Kimmeridge. (National Grid Reference: 909789.) 

Elegans Zone: 

4. KD 227—Clay containing shell fragments, medium dark grey in colour (N4), 
from 25 ft below the Yellow Ledge Stone Band, Kimmeridge. (National Grid 
Reference: 917780.) [This sample contains few microfossils. ] 

Scitulus Zone: 

5. CD 229—Clay, brownish grey in colour (5 YR 4/1), from 6 ft below the Cattle 
Ledge Stone Band, Cuddle. (National Grid Reference: 917780). 

Wheatleyensis Zone: 

6. CH 231—Clay, medium grey in colour (N5), from 22 ft below the Black Stone, 
Clavells Hard. (National Grid Reference: 920778.) 

7. RD 234—Clay, medium grey in colour (N4), from 13 ft above the Rope Lake 
Head Stone Band, Rope Lake Head. (National grid reference: 934785.) [No 
assemblage was obtained from this sample. ] 

Boundary of Pectinatus-Hudlestoni Zones: 

8. FD 236—Marl, medium dark grey in colour (N4), from + mile west of Fresh- 
water Steps, (National grid reference: 946773.) 

Pectinatus Zone: 

9g. FD 237—Marl, containing shell fragments, medium dark grey in colour (N4), 
from 2 ft above the Freshwater Steps Stone Band, + mile west of Freshwater Steps. 
(National grid reference: 946773.) 

10. ED 240—Marl containing shell fragments, medium grey in colour (N5), 
from 30 ft above the Freshwater Steps Stone Band, Egmont Bight. (National Grid 
reference: 948772). 

ir. ED 242—Clay, medium dark grey in colour (N4), from 60 ft above Freshwater 
Steps Stone Band, Egmont Bight. (National grid reference: 948772). 

12. HC 243—Clay, medium dark grey in colour (N4), from c. 100 ft below the 
Rotunda Nodules, in the base of Hounstout Cliff. (National grid reference: 951773). 

Rotunda Zone: 

13. CP 245—Clay containing shell fragments, medium light grey in colour (N6), 
from the Rotunda Nodule Bed, Chapmans Pool. (National Grid Reference: 956772). 

14. HC 246—Clay, medium grey in colour (N5), from 140 ft below the Massive 


FROM ENGLAND, SCOTLAND AND FRANCE 179 


Bed, Hounstout cliff (National grid reference: 950774). [Few specimens were ob- 
tained from this sample. ] 


ue Hounstout i 
| S Cliff at ares 
re) gmon 
fF Egmont Bay Point 
= w 
=: E 
s Pol = 2S 2 \ il 
Houns tout Cliff ao = 
4 Freshwater o 2 = 
55 8 (lili 
2) a vii 4 
@ Rope Lake Hole f 
wy Ih 
lavell’s Hard a s 2 f 
ae “i 
js o \I 
n x { 
Kimmeridge Bay e = | 
a =) 
lk: ic 
oO a 
o 7) 
Oo fo) 
5 Clavell’s Hard & 
as teh 
= 
wo | 
= = Yellow 
a S || Ledge 
a Cuddle a ‘Stone Band 
m5 S x ] 
a Ee | 
oS Maple 
mo] a | 
S | | Ledge 
a % ® {| Stone Band 
: & a Kimmeridge Bay \ 
=f\Fossil Forest 2 © y | | Washing 
| E S \ Ledge 
Ay cS > N (pf Stone Band 
Lulworth Cove | 5) 2 
ie 5 
o- Se rat 
vo 
-——\"EH Durdle Door % 
—SSSaae we 9° 
8 
=) 
<x 


Fic. 1. Sketch map of the Isle of Purbeck, showing the positions of the type sections of 
the Kimmeridge Clay. Section along the cliffs of Kimmeridge Clay (modified from 
Arkell, 1933). 


180 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


In the Weymouth District, the Jurassic rocks have been folded and faulted along 
a N-Sline. The Kimmeridge Clay, after a gap, reappears in Ringstead Bay, rising 
from the sea and partly hidden by slips of Chalk and Greensand. In this part of the 
Dorset Coast the Kimmeridge Clay is overlying conformably the Ringstead Coral 
Bed, at the top of the Oxfordian. 

Around Osmington Mills, the exposed clay in the cliffs mainly belongs to the 
Mutabilis and Pseudomutabilis Zones: it is quite deeply weathered and much slipped. 
The Cymodoce and Baylei Zones, with the Ringstead Coral Bed below, appear from 
time to time in the foreshore, as a result of periodic stripping of shingle by storms. 
An account of samples from the Baylei Zone at this locality was given earlier (Gitmez, 
1970). 

(2) Oxfordshire: 

The Kimmeridgian, together with the Portland and Purbeck Beds, occupies a 
small area, being partially concealed by the overlap of the Cretaceous strata. Three 
samples from the Pallasioides Zone were examined; these were collected from a 
quarry at Littleworth, Wheatley (National grid reference: 595055). 

t. LO 352—Clay, medium light grey in colour (N6), from 15 ft below the 

Wheatley Sands. 
2. LO 353—Clay, medium grey in colour (N5), from the quarry. 
3. LO 360—Clay, light olive grey in colour (5 Y 6/1), from the top of the 
Kimmeridgian, Littleworth. [No assemblage was obtained from this sample. | 
(3) Cambridgeshire: 

There are a few exposures of the Kimmeridge Clay in the north west of this area. 
Only one sample, from the Baylei Zone, was examined from this district: for details 
see Gitmez, 1970. 

(4) Warlingham, Surrey: 

The Warlingham borehole was drilled, under contract, in the Geological Survey 
programme of boring in 1956-1958 and was sited in a field beside the Woldingham 
Road, Warlingham (National Grid reference: TO 34765719). The boring commenced 
in Middle Chalk and passed through the Cretaceous and Jurassic rocks, terminating 
in the Lower Carboniferous at a depth of 5001 ft. At this locality the Kimmeridge 
Clay is 703 ft thick (between 2284 ft and 2987 ft in depth). 

Twenty-nine samples, at 25 ft intervals, from the Rotunda Zone to the Mutabilis 
Zone, were studied for their organic-shelled microplankton content. These 
Kimmeridge Clay samples are between light bluish grey and medium bluish grey in 
colour (5 B 6/1), representing the zones as follows: 


Rotunda Zone: 
1. WB 29 from 2285’7 ” depth. 
2. WiB28. 5.8 2310/6 tudepth. 
3. WB27 ,, 23350” depth. 
Pectinatus Zone: 
4. WB 26 from 2359’9 ” depth. 
5. WB25 ,, 2384’9” depth. [Few specimens obtained. ] 
6. WB24 ,, 2409’9” depth. 


FROM ENGLAND, SCOTLAND AND FRANCE 181 


Hudlestoni Zone: 
7. WB 23 from 2434’6 ” depth. 
8. WB22 ,, 24596” depth. [Few specimens obtained. ] 
9. WBaxi ,, 2485’0” depth. [Few specimens obtained. | 
Wheatleyensis Zone: 
10. WB 20 from 2510’0 ” depth. 
om, WBig-,, 25353 ° depth. 
mw. WBI8 ,, 25600” depth. 
Scitulus Zone: 
13. WB17 from 2584’9 ” depth. 
14. WB16 ,, 2610’0” depth. 
Elegans Zone: 
15. WB15 from 2635’3 " depth. 
Autissiodorensis Zone: 
16. WB 14 from 2660’1 " depth. 
ig WBI3 ,, 2068473” depth. 
18. WBiz2 ,, 27093” depth. [Few specimens obtained.] 
Eudoxus Zone: 
mg. WB 11 from 2734‘11 ” depth. 
ga, WBi0 ,, 2760'5 "depth. 


ae WE 9 ,, 2785'2" depth. 
22, WE 8 ,, 28106” depth. 
Boe WE 7 ,,.. 28347 ” depth. 
ae WE 6 ,; 2860%0.” depth. 
ae WR 5 ,, 2885/1 " depth. 
20, WB 4 ,, 29106.” depth. 


Mutabilis Zone: 

27. WB 3 from 2935’2 ” depth. 

ze WB 2 ,, 2950'5 ” depth: 

aoe WB i ., 2984’7°" depth. 
(5) Isle of Skye (Staffin Bay): 

Three samples were examined from the Baylei Zone of Staffin Bay; these have 
been fully described by Gitmez, 1970. 

(6) Eathie Haven (South of Cromarty): 

The Kimmeridgian strata are visible in a narrow shore strip exposed only at low 
tide. The beds consist of carbonaceous shales, sandstones, bituminous shales and 
limestones. The total thickness has been calculated as approximately 38 m 
(Waterston, 1951, p. 33); the apparent thickness is less than the real thickness, 
because of the displacements consequent upon folding, which render it difficult to 
determine the thickness accurately (Text-fig. 2 a, b). Only one sample, from the 
Cymodoce Zone, was examined: 

CS 421—Shale, olive black in colour (5 Y 2/1), from the first Meleagrinella Band of 
Eathie. (National grid reference: 778636.) 

(7) The Boulonnais, Pas-de-Calais, France: 
The Kimmeridgian rocks are well exposed along the coast of the Boulonnais (see 


182 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


Oo . 
. cS a Middle Old Red Sandstone 


Kimmeridgjan 


Fic. 2. A. Sketch map showing the geology around Eathie, Cromarty (after Waterston, 
1952). 


Ager and Wallace, 1966a, b). Eight samples were studied, seven of which (obtained 
from the basal formations, which are the equivalent of the Baylei Zone in Dorset) 
were described in a previous paper (Gitmez, 1970). In addition, one was obtained 
from the Subplanites Zone sensu Arkell, here considered probably equivalent to the 
Scitulus Zone of Cope, 1967. 

CC 453—clay, light grey in colour (N7), from Argiles de la Créche, north of Cap de 
la Créche. No microfossils were recovered. 
(8) Normandy: 

Only the lower Kimmeridgian is represented in Normandy: it appears beneath the 
unconformable Cretaceous and comprises clays and limestones with ammonites 


FROM ENGLAND, SCOTLAND AND FRANCE 183 


indicative of the Mutabilis, Cymodoce and Baylei Zones. Two samples were 
studied, one from the Baylei Zone (described by Gitmez, 1970), the other from the 
Cymodoce Zone: 

BN 179—Marls, light olive grey in colour (5 Y 6/1), Benerville, Normandy. 
(9) Le Havre, Seine Inférieure: 

On the shore at Cap de la Héve, clays and limestones of Kimmeridgian age are 
exposed, beneath the Cretaceous unconformity, at the foot of the cliffs. Three 


Mutabilis Zone 


_Jt.6ins. —~Al-= 1-7-7 - 7 - Second Limestone 


lft é6ins. —> £ 


t 
1Si fit: 
4 


lft. > Gop First Limestone 


12 ft- 


£ 2 ft. —> Meleagrinella Band 
S 
o 
Vv 
° 
me} 
° 
f 250 ft 
U 
5 ; So 
ot -* |Astarte Muds 
----F--- === || Olive Black Shale 
e ‘ 
g ‘\Green Grey Mudstone 
a 
~ 
o 
a 


Fic. 2. B. The section of the strata at Eathie, Cromarty (after Waterston, 1952). 


184 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


samples were studied: two of these, from the Baylei Zone, have already been 
described (Gitmez 1970); the third sample was from the Mutabilis Zone. 

HF 395—Marls, light olive grey in colour (5 Y 6/1), from the Marnes a ammonites, 
Cap de la Heéve. 

(10) Lorraine: 

In the east of the Paris basin, the Cretaceous usually rests on the Oxfordian; 
occasionally, however, some Lower Kimmeridgian rocks are still present below the 
unconformity. Only one sample was obtained from Lorraine: 

LF 368—Marl, yellowish grey-light olive grey in colour (5 Y 7/1), collected from 
the Cymodoce Zone, about 2 ft above the Calcaires a Astartes. Roadside, about 1 
km east of Gondrecourt. [This sample contains very few microfossils. | 
(1r) Mont Crussol (Rhone Valley): 

The Jurassic rocks of Mont Crussol comprise a continuous and well-exposed, 
dominantly calcareous sequence from Upper Bathonian to Tithonian (see Karvé- 
Corvinus, 1966). The Middle and Lower Tithonian (which is equivalent to the 
Upper and Middle Kimmeridgian sensi anglico) is represented by limestones of 
various sorts. Thick limestones form the Kimmeridgian stage in its restricted, 
Continental acceptation (the Tenuilobatus, Pseudomutabilis and Beckeri Zones 
representing the Lower and Middle Kimmeridgian, sensu anglico). 

Eight samples were examined, the first sample yielding very few microfossils, the 
others none at all; 

1. MR547—Limestone, yellowish grey-light olive grey in colour (5 Y 7/1), from 
the lower boundary of the Platynota Zone (?Baylei Zone), small quarry above the 
west side of the Ravin d’Enfer. 

2. MR548—Limestone, light grey in colour (N7), from the lower part of the 
Ataxioceras Zone (Cymodoce-Mutabilis Zones), same locality. 

3. MR549—Limestone, very light grey in colour (N8), from the top of the 
Ataxioceras Zone, same locality. 

4. MR550—Limestone, pinkish grey in colour (5 YR 8/1), from the Idoceras 
balderum Bed, same locality. 

5. MR552—Limestone, yellowish grey in colour (5 Y 8/1), from the fossil band 
at the base of Pseudomutabilis Zone (i.e. Autissiodorensis Zone), ridge top above the 
Carriere Mallet. 

6. MR553—Limestone, yellowish grey-light olive grey in colour (5 Y 7/1), from 
the Pseudomutabilis Zone, ridge top. 

7. MR554—Limestone, light olive grey in colour (5 Y 6/1), from the lower 
boundary of the Beckeri Zone (i.e. Autissiodorensis-Elegans Zones), ridge top. 

8. MR555—Limestone, pinkish grey in colour (7 YR 8/1), from the Beckeri 
Zone, near the summit of the ridge. 

(12) The Jura Mountains (Southern French Jura): 

As the original type locality for Alexander von Humboldt’s “‘Jurassic’’, this region 
is of particular interest. The most important recent work has (rather unexpectedly) 
been done by English geologists (see Ager and Evamy, 1963). The sequence is 
again predominantly calcareous and exposure is intermittent but adequate. Three 


FROM ENGLAND, SCOTLAND AND FRANCE 185 


samples from the Oignon Beds and two samples from the Virieu Limestone were 
examined: 

1. OF 485—Limestone (a well-bedded calcilutite), yellowish grey in colour 
(5 Y 8/x), from the road side, Montard d’Oignon (type locality). Mutabilis Zone. 

2. OF 486—Limestone, yellowish-light olive grey in colour (5 Y 7/1), from the 
top of the Oignon Beds, beneath a pisolite; roadside west of Lac du Chavoley. 
Mutabilis Zone. 

3. OF 487—Pisolitic limestone, yellowish grey in colour (5 Y 8/1), from the 
junction of Oignon Beds and Bedded Virieu, 2 km north of St. Germain-de-Joux 
(Mutabilis Zone). [This sample contains few microfossils. | 

4. BV 488—Limestone, greenish grey in colour (5 GY 6/1), from the base of 
Bedded Virieu (Lower Kimmeridgian), calcilutite above pisolite. 

5. MV 489—Limestone, pinkish grey in colour (5 YR 8/1), from the Massive 
Virieu (?Upper Kimmeridgian), 200 yards west of Virieu-le-Grand (type locality). 
[The sample yielded very few microfossils. | 


Ill. SYSTEMATIC SECTION 
Class DINOPHYCEAE Pascher 
Sub-class DINOFEROPHYCIDAE Bergh 
Order DINOPHYCIALES Lindemann 
Cyst-Family FROMEACEAE Sarjeant & Downie, 1966 

Genus CHYTROEISPHAERIDIA Sarjeant, 1962 

emend. Downie, Evitt & Sarjeant, 1963 
Chytroeisphaeridia chytroeides Sarjeant, 1962b 

Plate 1, figure 2 


1962b Leiosphaeridia (Chytroeisphaeridia) chytroeides Sarjeant, 493-4, pl. 70, figs 13, 16, text- 
figs 11-12, tables 2-3. 

1963 Chytroeisphaeridia chytroeides (Sarjeant); Downie, Evitt & Sarjeant, 9. 

1964a Leiosphaeridia chytroeides Sarjeant; Sarjeant, table 3. 

1964 Chytroeisphaeridia chytroeides (Sarjeant); Downie & Sarjeant, 103. 

1967b C. chytroeides (Sarjeant); Sarjeant, table III. 

1968 C. chytroeides (Sarjeant); Sarjeant, pl. III, fig. 10, table 2B. 

1970 C. chytroeides (Sarjeant); Gitmez, pl. 14, fig. 5, table 4. 

1970 C. chytroeides (Sarjeant); Gocht, 152, pl. 34, figs 20-24. 


FIGURED SPECIMEN: I.G.S. slide PK10zA: Sample WB 2, Kimmeridge Clay. 
H.M. Geological Survey Borehole, Warlingham, Surrey, at 2959 feet 5 in. depth. 
Lower Kimmeridgian (Mutabilis Zone). 


DIMENSIONS: Figured specimen: length (apex lacking) 45u, breadth 48u. Range 
of the English specimens: length (apex lacking) 12-72u, breadth 18-80u,, measured 
specimens 1029 innumber. Range ofthe Scottish specimens (40 specimens measured) : 
length (apex lacking) 20-50u, breadth 22-75u. 161 specimens from French assem- 


186 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


blages were measured: length (apex lacking) 16-62u, breadth 22-65. There is no 
significant difference between the size of specimens from different zones in the 
Kimmeridgian or between English, Scottish and French specimens. The Kim- 
meridgian specimens exhibit a somewhat wider dimensional range than do the 
Oxfordian specimens; diameters of the latter, as quoted by Sarjeant (1962b), are 
30-60u. 

OBSERVED RANGE: Kimmeridgian (Baylei to Pallasioides). 

TOTAL KNOWN RANGE: ?Lower Bathonian: certainly Callovian (Mariae) to 
Kimmeridgian (Pallasioides). 

REMARKS: This species occurs in moderate abundance in all Kimmeridgian 
assemblages from England, Scotland and France, being most abundant in the 
Lower Kimmeridgian, numerically somewhat reduced in the Upper Kimmeridgian 
(Pallasioides Zone). 


Chytroeisphaeridia mantelli sp. nov. 
Plate 1, figures 3-4; Plate 12, figure 3 


DERIVATION OF THE NAME: Named in honour of Gideon Algernon Mantell, pioneer 
of the study of microplankton. 

D1aAGnosis: Shell subspherical to elongate. The periphragm is coarsely granular 
and bears an irregular scatter of tubercles and of low knobs, giving it a somewhat 
warty appearance. An apical archaeopyle is present, with slits extending posteriorly 
along presumed reflected sutures, producing a ragged appearance. The operculum 
most often remains attached to the ventral side of the shell. 


HoLtotyre: I.G.S. slide PK116, Sample WB13, Kimmeridge Clay, H.M. 
Geological Survey Borehole, Warlingham, Surrey, at 2684 ft 2 in. depth. Lower 
Kimmeridgian (Autissiodorensis Zone). 


PARATYPE A: I.G.S. Slide PK114, Sample WB 13. 


PARATYPE B: BM(NH) slide V.56338 (1) sample CH 231, from 22 ft below the 
Blackstone, Clavells Hard, Dorset. Middle Kimmeridgian (Wheatleyensis Zone). 


DIMENSIONS: Holotype: overall length 65u, breadth 60u. Paratype A: overall 
length (apex lacking) 60u, breadth 65u. Paratype B: overall length (apex lacking) 
65u, breadth 7ou. Range of Lower Kimmeridgian specimens: length (apex lacking) 
25-75u., breadth 30-65u, measured specimens 12 in number. Range of Middle 
Kimmeridgian specimens: length (apex lacking) 40-80y, breadth 50-75u, measured 
specimens 16 in number. Range of Upper Kimmeridgian specimens: length (apex 
lacking) 23-70, breadth 28-75u, measured specimens 12 in number. 

According to these measurements, the species attained its largest size in the Middle 
Kimmeridgian. 

DescripTIon: The thick shell wall is apparently composed of two layers: the 
inner layer thin, the outer layer making up almost the entire wall thickness. The 
ornamentation of the periphragm is of three types: coarse granules, small irregularly 


FROM ENGLAND, SCOTLAND AND FRANCE 187 


formed lumps (verrucae) and rounded tubercles, irregularly scattered. A tabulation 
is indicated only by the slits; there is no suggestion of a cingulum. The sulcal notch 
was seen only in specimens in which the operculum was completely lost; it was not 
perceptible in specimens with the operculum still attached. This is considered to 
indicate that when the operculum is present, it is attached to the ventral side of the 
cyst. 

REMARKS: C. mantelli differs from previously described species of the genus in 
its relatively thick wall, the ornamentation of the periphragm and the form of its 
apical archaeopyle. The most similar species is C. euteiches Davey (1969), from the 
Cenomanian; but the shell wall of this new species is not so thick as in C. euteiches 
(2-3u as quoted by Davey). Although C. euteiches has an apical archaeopyle, it is 
angular in outline and generally narrower, whereas in C. mantelli the archaeopyle is 
characteristically wide, with deep slits passing posteriorly from its margin. (Davey 
mentioned that the apical archaeopyle of C. euteiches also has small slits extending 
posteriorly from the margin.) 

This new species, in its surface ornamentation and wall structure, also shows a 
broad accord with the diagnosis of Tenwa as emended by Sarjeant (1968b). Since 
cingulum and sulcus are not indicated and since, although the cyst wall shows a 
considerable ornament, spines are not present, it was allocated to the genus 
Chytroeisphaeridia. However, it should be noted that the form of the archaeopyle 
is closer to that of Tenua than to that of typical species of Chytroeisphaeridia. This 
species is thus intermediate in morphology between the genera Chytroeisphaeridia 
and Tenua. 

C. mantelli was recorded from all zones of the Kimmeridge Clay; it was more 
abundant in the Middle Kimmeridgian (Eudoxus to Elegans Zones) than in the other 
subdivisions of the Kimmeridgian. Thirty-seven specimens from England and 
five specimens from France were examined; it was not observed in the Scottish 
assemblages. 


Chytroeisphaeridia pococki Sarjeant, 1968 
Plate 1, figure 5 
1965 Chytroeisphaeridia sp. Sarjeant, pl. 1, fig. 13. 


1968 Chytroeisphaeridia pococki Sarjeant, 230, pl. 3, fig. 9. 
1970 C. pococki Sarjeant; Gitmez, pl. 9, fig. 7, pl. Io, fig. 3, table 4. 


FIGURED SPECIMEN: BM(NH) Slide V.53961(3). Sample SC 444, from Great Ouse 
River Board Pit, Stretham, Cambridgeshire. Lower Kimmeridgian (Baylei Zone). 


Dimensions: Figured specimen: length (apex lacking) 18u, breadth 22u. Range 
of Lower Kimmeridgian specimens: length (apex lacking) 18-85, breadth 22-78y, 
measured specimens 178 in number. 

Range of Middle Kimmeridgian specimens: length (apex lacking) 35-75, breadth 
35-80, measured specimens I13 in number. 

Range of Upper Kimmeridgian specimens: length (apex lacking) 28-80y, breadth 
35-80u, measured specimens 61 in number. 

B 


188 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


There is no difference in dimensions between the English, Scottish and French 
specimens. Lower and Middle Kimmeridgian specimens are of comparable 
dimensions to those of the Oxfordian holotype (dimensions, as quoted by Sarjeant; 
length [apex lacking] 45u, breadth 55,). 


OBSERVED RANGE: Kimmeridgian (Baylei to Pallasioides). 


TOTAL KNOWN RANGE: Callovian (Lamberti to Mariae) and Kimmeridgian (Baylei 
to Pallasioides) of Europe; Upper Jurassic of Canada. 


REMARKS: C. fococki is present in the Kimmeridgian assemblages from England, 
Scotland and France: although present at all levels, it was found to be most abundant 
in the Lower and Middle Kimmeridgian, being especially common in the Warlingham 
borehole samples. 


Genus FROMEA Cookson & Eisenack, 1958 
Fromea warlinghamensis sp. noy. 
Plate 1, figures 6, 8; Plate 9, figures 5-6 


DERIVATION OF THE NAME: Named after the type occurrence in the Warlingham 
borehole, Surrey. 


D1aGnosis: Cyst broadly ovoidal to almost spherical, with a relatively thick wall. 
Archeopyle apical, subhexagonal to almost circular; a rather rounded projection, 
not always observable, appears to be a sulcal tongue. The shell surface is densely 
and coarsely granular. A cingulum is indicated by indentations at the margins; 
less frequently, it is traceable across the surface. 


Ho.otyPeE: I.G.S. slide PK115, Sample WB 13, Kimmeridge Clay, H.M. Geological 
Survey borehole, Warlingham, Surrey, at 2684 ft 3in. depth. Lower Kimmeridgian 
(Autissiodorensis Zone). PARATYPES (a) BM(NH) slide V.56339(2), sample 
CH 231, slide V.56339(2) Kimmeridge Clay 22 ft below the Black Stone (Wheatley- 
ensis Zone), Clavell’s Hard, Dorset. (b) BM(NH) slide V.56340(1), sample LO 353, 
top of Kimmeridge Clay (Pallasioides Zone), Littleworth, Oxfordshire. 


Dimensions: Holotype: length (apex lacking) 47-3, breadth 4o-5u. Paratype 
(a): length (apex lacking) 81-5u, breadth 79:5u. Paratype (b): length (apex lacking) 
71y, breadth 65u. Range of specimens observed (25 in number); length (apex 
lacking) 42-95y, breadth 40-88y. 

DESCRIPTION: The pronounced original sphericity characteristic of this species 
results in a variety of structures produced by compression ; paratype (a) in particular, 
shows an irregular series of bulges. The granules are of variable size and are 
characteristically circular; the distinctly polygonal granules on the outbulges on 
paratype (a) probably result from pressure by mineral grains. The wall appears 
to be composed of a single layer: it may be as much as 2—3y in thickness. 


OBSERVED RANGE: Kimmeridgian (Autissiodorensis to Pallasioides Zones). 


REMARKS: This new species is distinguished from Fromea amphora, the only other 
species to date placed in this genus, by its much more spherical shape and coarsely 


FROM ENGLAND, SCOTLAND AND FRANCE 189 


granular surface. The known range of the latter species is Barremian to Albian 
(Cookson and Eisenack, 1958): the stratigraphic hiatus between the type species 
and this Upper Jurassic species may well be removed by future studies. 


Genus TENUA Eisenack, 1958c emend. Sarjeant, 1968 
Tenua capitata (Cookson & Eisenack, 1960b) comb. nov. 
Plate 1, figures 11-12 


1960b Hystrichosphaeridium capitatum Cookson & Eisenack, 252. pl. 39 fig. 9. 
1964 4H. capitatum Cookson & Eisenack; Sarjeant, table 3. 

1964 H. capitatum Cookson & Eisenack; Downie & Sarjeant, 120. 

1970 Tenua cf. capitata (Cookson & Eisenack); Gitmez. pl. 10, fig 4. table 4. 


DESCRIPTION: Cyst spherical to elongate, with an apical archaeopyle and rounded 
antapex, bearing processes whose length sometimes reaches to one-third of the shell 
breadth and which number around fifty. The processes are hollow, capitate or 
briefly bifurcate, their distribution appearing random. 


FIGURED SPECIMEN: BM(NH) slide V.56341(1) sample HF 185, from the Exogyra 
Marls, c. 1 m above the Upper Hard Band, Cap dela Héve, Le Havre. Lower 
Kimmeridgian (Baylei Zone). 

Dimensions: Range of the English specimens: length (apex lacking) 30-65y, 
breadth 22-50u (7 specimens measured). Range of the French specimens: length 
(apex lacking) 30—40u, breadth 22—33u (2 specimens measured). 3 specimens from 
the Scottish assemblages were recorded and measured: length (apex lacking) 30-58y, 
breadth 30-58. Overall range of process length (all localities) 3-10. There is not 
much difference between these dimensions and the dimensions of the Australian 
specimens quoted by Cookson and Eisenack (length 64-66y, breadth 28—44u,, process 
length 8). 


OBSERVED RANGE: Kimmeridgian (Baylei to Mutabilis). 
TOTAL KNOWN RANGE: Jurassic (Oxfordian to Kimmeridgian). 


REMARKS: This species, under the name of Hystrichosphaeridium capitatum, has 
previously been recorded from the Oxfordian to Kimmeridgian of Australia by 
Cookson and Eisenack. It is transferred to the genus Tenwa on the basis of shell 
outline, the presence of an apical archaeopyle, and the form and number of the 
processes. The processes do not clearly reflect any tabulation. 

Well-preserved specimens were observed in moderate numbers in samples from the 
Lower Kimmeridgian only; nine specimens from the Baylei Zone of England and 
three specimens from that zone in France; three specimens from the Cymodoce 
Zone of Scotland; and two specimens from the Mutabilis Zone of England were 
recorded. 

These specimens are similar to that figured by Cookson and Eisenack. Although 
the number of the processes appears greater than in the Australian specimens, it was 
not possible to make precise comparisons since the number of processes was not 
mentioned by Cookson and Eisenack. 


190 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


Tenua echinata sp. nov. 
Plate 1, figures 1, 9 
1969 Tenua sp. Gitmez, 245-6 pl. 8, fig. 3, text-fig. 3, table 4. 


DERIVATION OF THE NAME: Latin, echinatus, spiny, prickly; referring to the spiny 
surface of the shell. 


Di1aGnosis: Cyst spherical, subspherical or broadly ovoidal, covered with spines 
and looking like a prickly ball. Spines very short, broad-based and conical, 
uniformly distributed over the whole surface, over 200 in number. There is no 
indication of tabulation, cingulum or sulcus. Archaeopyle usually present, apical 
in position; the operculum usually remains attached on one side but is sometimes 
completely lost. 


HototypPEe: BM(NH) slide V.52796(1). Sample OM 131, from the base of the 
Kimmeridge Clay, Liostrea delta Bed, Osmington Mills, Dorset. Lower Kimmeridgian 
(Baylei Zone). 

PARATYPE: I.G.S. slide PK.119, sample WB 16, from H.M. Geological Survey 
borehole, Warlingham, Surrey, at 2610 ft depth. Middle Kimmeridgian (Scitulus 
Zone). 

DIMENSIONS: Holotype: overall length 50u, breadth 50u; length without apex 
43u.; length of the spines 2u. 

Paratype: overall length 72u, breadth 60; length of the spines 2-5u. 

Overall range of the English specimens (15 specimens measured): length 45—90u, 
breadth 40-80u, length without apex (3 specimens were observed without apex) 
43-60u; length of the spines 1-5-2-5u. 

Dimensions of the single French specimen encountered: length (apex lacking) 38u, 
breadth 4ou; length of spines 2y. 

DescripTIon: The shell surface is smooth. The apex is typically detached in 
archaeopyle formation. The margin of the archaeopyle is roughly polygonal, with 
tears extending from the angles along the presumed lines of a reflected tabulation. 
When the operculum remains attached on one side, this side is probably the ventral 
side. The spines appear to be solid. 

OBSERVED RANGE: Kimmeridgian (Baylei to Pallasioides Zones). Not recorded 
to date from the Mutabilis, Autissiodorensis and Elegans Zones. 

REMARKS: This new species of Tenwa differs from previously described species of 
the genus in its characteristic shape and in the nature of its spines. It is an in- 
frequent species: 15 specimens from English assemblages and only a single specimen 
from France were recorded. 


Tenua sp. 
Plate 1, figures 7, 10 
1970 Chytroeisphaeridia pococki Gitmez: pl. 9, fig. 8, table 4. 
DESCRIPTION: Shell spheroidal to broadly ovoidal, densely granular. The shell 


FROM ENGLAND, SCOTLAND AND FRANCE IQI 


wall may or may not be composed of two layers: if the wall is indeed bipartite, then 
both layers are thin. The outer wall (periphragm?) bears numerous spines whose 
character is seen clearly only at the margins, especially around the antapex. The 
spines are slender and short: the relative length of particular spines is, however, 
highly variable, median spines being consistently shorter than those of the antapical 
region. At their tips, the spines are most often knobbed, capitate or briefly bifurcate. 
The cingulum is faintly indicated by two parallel lines in the equatorial region. An 
apical archaeopyle is developed, with a scalloped margin suggesting partial reflection 
of a tabulation. 


FIGURED SPECIMEN: BM(NH) slide V.53619(1). Sample SS 627, from too ft 
above the second dolerite sill, Staffin Bay, Skye. Lower Kimmeridgian (Baylei 
Zone). 


Dimensions: Figured specimen: length (apex lacking): 50u, breadth 55u, spine 
length 2-3y. 

REMARKS: This specimen was mentioned earlier as Chytroeisphaeridia pococki by 
one of the authors (Gitmez, 1970), but later examination by high power phase 
contrast objective showed the presence of spines and other details which made it 
clear that this specimen is different from C. pocockit. The observation was based on 
a single, fairly well preserved specimen. It is generally similar to Tenua verrucosa 
Sarjeant and Tenua villersense Sarjeant; the shape of the spines compares closely 
with those of T. villersense, but they are very short, as in T. verrucosa. This may be 
a representative of an undescribed species intermediate between 7. verrucosa and 
T. villersense. 


Cyst-Family GONYAULACYSTACEAE Sarjeant & Downie, 1966 
Genus CRYPTARCHAEODINIUM Deflandre, 1939b emend. Gitmez, 1970 


Cryptarchaeodinium calcaratum Deflandre, 1939b emend. Gitmez, 1970 


1939b Cryptarchaeodinium calcavatum Deflandre, 145, pl. 6, fig. 6. 
1941a C. calcavatum Deflandre; Deflandre, 19, pl. 5. figs. 7-9; text-figs 9-10. 


1962 C. calcavatum Deflandre; G. & M. Deflandre, fiche 1908. 
1964 C. calcavatum Deflandre; Downie & Sarjeant, 104. 

1964 C. calcavatum Deflandre; Eisenack, 153-4. 

1964 C. calcavatum Deflandre; Sarjeant, table 2. 


1965 C. calcavatum Deflandre; Gorka, 303, pl. 2, figs 3-5, table 1. 
1967b C. calcavatum Deflandre; Sarjeant, table IV. 
1970 C. calcavatum Deflandre; Gitmez, 246-8 pl. 1, figs 1-2, text-fig. 4, table 4. 


OBSERVED RANGE: Kimmeridgian (Baylei and Rotunda Zones). 

TOTAL KNOWN RANGE: ?Oxfordian to Kimmeridgian (Rotunda). 

Remarks: Deflandre first observed this species in the Kimmeridgian assemblages 
from Orbagnoux (1939); a fuller diagnosis was given later (1941). In 1965, Gorka 
recorded this species for the first time from Poland, in sediments considered to be of 


Oxfordian age. She observed the archaeopyle formation (by loss of plate 3’’) and 
determined a tabulation similar to that of the Kimmeridgian specimens, except that 


192 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


she mentioned the presence of a second antapical plate: this plate (2’’’’) was never 
observed in the Kimmeridgian specimens. According to the measurements quoted 
by Gorka, the Polish specimens from the Oxfordian are larger than the English and 
French Kimmeridgian specimens, with longer sutural spines. The attribution of 
these Polish specimens to the species C. calcavatum must, all in all, be considered 
very doubtful. 


Cryptarchaeodinium cf. calcaratum 
Plate 2, figure 3; text-figure 3 


DESCRIPTION: Shell spherical, with a small, blunt apical horn and rounded, dome- 
shaped antapex. Tabulation: 4’, 6’, 6c, 7’, 2p, ?Ipv and 1”. Apical plates 
small; plates 1’ and 3’ form the apical horn. The precingular plates are more or less 
constant in shape and size, the boundary between plates 5” and 6’ not being clear. 
Cingulum equatorial, a laevorotatory spiral; cingular plates 3c and 4c are the largest 
and occupy the dorsal side. The postcingular plates are of variable shape and size: 
plates 1’”, 2’”, and 7’” are relatively small and triangular, plate 4’ (the largest) 
is more or less square. Two posterior intercalary plates, rp and 2p, are present and 
placed on either side of plate rpv: the boundary between Ip and Ipv was not clear. 
Plate 2p is very small. The single antapical plate (1’’’’) is convex and its greatest 
portion is positioned on the dorsal side of the cyst: this does not seem to be the result 
of distortion in compression. The sulcus is short, being very wide on the epitract 
but narrowing on the hypotract. On the plate boundaries, crests of irregularly 
spinous character rise up: some crest spines are briefly bifurcate. The shell surface 
is minutely granular. An archaeopyle was not observed. 


Fic. 3. Cvryptarchaeodinium cf. calcavatum Deflandre. General appearance, showing the 
tabulation: left, in ventral view; right, in dorsal view. BM(NH) slide V.56342 (1). 
X Cc. 1400, 


FROM ENGLAND, SCOTLAND AND FRANCE 193 


FIGURED SPECIMEN: BM(NH) slide V.56342(1). Sample CS 421, from the first 
Meleagrinella Band of Eathie, Cromarty. Lower Kimmeridgian (Cymodoce Zone). 


DIMENSIONS: Overall length 40-50y, breadth 35-5ou, horn length 5—6y, length of 
the spines on the sutures 4-6. Two specimens were measured. 


REMARKS: Two specimens observed, one from the Lower Kimmeridgian (Cymodoce 
Zone) of Scotland and one from the Upper Kimmeridgian (Pectinatus Zone) of 
Dorset, are similar to C. calcaratum except in their possession of an apical horn and in 
slight differences in the shape of the plates on the hypotract. 


Genus GONYAULACYSTA Deflandre, 1964 emend. Sarjeant, 1969 
Gonyaulacysta cauda sp. nov. 
Plate 2, figures I-2, 4-5 
1969 Gonyaulacysta sp. B Gitmez, pl. 6, fig. 3, text-fig. 14, table 4. 


DERIVATION OF THE NAME: Latin, cauda, tail, appendage; in reference to the 
antapical spines. 


Diacnosis: The broadly ovoidal cyst possesses a poorly developed apical horn with 
long spines arising from its tip. Tabulation: 4’, 1a, 6”, 6c, 6’, Ip, Ipv and 1’’”. 
Spiny crests separate the plates. The single antapical plate is characteristically 
surrounded by long (nearly three times longer than the other sutural spines), thin, 
simple spines. Cingulum helicoid, laevorotatory ; sulcus moderately broad, extending 
on both epitract and hypotract to the same length. Surface densely granular. 
Precingular archaeopyle, if present, formed by loss of plate 3”’. 


Horotyre: BM(NH) slide V.53965(2) from the sample CC 447, Argiles de Moulin 
Wibert of Cap de la Créche, Boulonnais, France. Lower Kimmeridgian (Baylei 
Zone). 


PARATYPE: BM(NH) slide V.56343(1). Sample HC 243, from c. 100 ft below 
Rotunda Nodules, base of Hounstout Cliff, Dorset. Upper Kimmeridgian (Pectinatus 
Zone). 


DIMENSIONS: Holotype: overall length 78u, breadth 50y, apical horn length 8y; 
length of the sutural processes 3-5u, antapical processes 8; breadth of the cingulum 
3-Su- 

Paratype: length 80u, breadth 65u, apical horn length 12u, antapical processes 
length row. 

A third specimen could not be measured because of its poor preservation. 


DEscriPTION: The slightly helicoid, laevorotatory cingulum of moderate breadth, 
divides the cyst into two unequal parts. The conical epitract terminates in a 
poorly developed apical horn, the hypotract is dome-shaped. The epitract is larger 
than the hypotract, almost two-thirds of the shell length. Apical plate 
I’ is elongate, its anterior and posterior ends being narrow; together with 
plate 3’, it forms the apical horn. Plate 2’ is quite large; 4’ is the smallest of 
the apical plates. The single anterior intercalary plate 1a is large; as a result plate 


194 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


6” is reduced. The precingular plate 1” is long and narrow; plates 2”, 3’, 4’ and 
5’ are large. One of the specimens observed has a precingular archaeopyle, formed by 
loss of plate 3’. Six postcingular plates occupy the hypotract, together with the 
single antapical plate and the posterior plates. Plate 1’’’ is quadrate and as small 
as the adjacent sulcal plate; all the other postcingular plates are relatively large. 
A crescent-shaped plate, rpv, separates the sulcus from antapical plate 1’’’’.. The 
boundary surrounding the antapical plate 1’’’’ bears longer spines than the other 
sutural spines. All the sutural spines are simple, solid, thin, threadlike. 


REMARKS: This new species is rare, only three specimens being recorded from the 
following samples: CC 447, RB 219, HC 243 (The first two are from the Baylei Zone, 
the last from the Pectinatus Zone). It has not been observed in the Middle 
Kimmeridgian. Two specimens were well preserved, with tabulation and mode of 
archaeopyle formation easily determinable, but the third was badly preserved. 
With their long spines distributed like tassels around the antapex, these specimens 
are different from all previously described proximate dinoflagellate cysts. 


Gonyaulacysta cf. giuseppei (Morgenroth, 1966) Sarjeant, 1969 
Plate 3, figures 3-4, text-figure 4 


DESCRIPTION: Cyst subspherical to globular, with the tabulation 4’, 6’’, 6c, 6’”’, 
ip and 1’’’’.. The cingulum is strongly helicoid, laevorotatory, dividing the cyst 
into two equal parts: the epitract ends in a short apical horn, the hypotract has a 
conical aspect with very convex antapex. The apical plates combine to form the 


ee Bt 


Fic. 4. Gonyaulacysta cf. giuseppei (Morgenroth). Showing tabulation and archaeopyle: 
left, in ventral view; right, in dorsal view. BM(NH) slide V.56344. ™ c. Ioro. 


FROM ENGLAND, SCOTLAND AND FRANCE 195 


apical horn. The precingular plates, except plate 6’’, are quite large. Plate 3” 
is subtriangular in shape and lost in archaeopyle formation, together with some 
parts of the cingulum (plate 3, figure 4). The postcingular plates are of variable 
size and shape: plates 1’ and 2’”’ are both reduced to accommodate the long posterior 
intercalary plate 1p. Plates 3’ and 4’” are the largest of all the plates. A single 
convex plate occupies the antapex. The sulcus is broad, extending between the 
apex and the antapex. The surface of the shell is granular. Crests on the plate 
boundaries are low and membraneous. 


FIGURED SPECIMEN: BM(NH) slide V.56344(1). Sample CC 448 from Calcaires 
de Moulin Wibert, south side of Cap de la Créche, Boulonnais. Lower Kimmeridgian 
(Baylei Zone). 

DIMENSIONS: Figured specimen: overall length 78u, breadth 62u, length of apical 
horn 64. Range of the observed specimens: overall length 65—78y, breadth 58-62u, 
horn length 5-6u. (Measured specimens 4 in number.) Morgenroth gave the 
following dimensions for G. giusepper (Eocene): length 67-87y, breadth 67—78u, horn 
length 6-8u. The specimens from the Kimmeridgian are thus slightly smaller than 
the true G. giusepper. 


REMARKS: Four specimens from the Lower Kimmeridgian assemblages of the 
Baylei and Mutabilis Zones (one from France, three from England) are closely similar 
to G. giusepper, recorded from the Lower Eocene of Germany by Morgenroth (1966). 
The only major difference is in the shape of the precingular archaeopyle; G. giwsepper 
has a very large, markedly polygonal archaeopyle, but in the Kimmeridgian 
specimens observed, the archaeopyle is somewhat smaller and tapers so markedly 
towards the apex that it appears almost triangular. Since the big stratigraphical 
gap makes it improbable that these specimens are conspecific with G. giuseppet, 
they are compared with, rather than attributed to that species. 


Gonyaulacysta globata sp. nov. 
Plate 3, figures 1-2; text-figures 5 A-B 


DERIVATION OF THE NAME: Latin, globus, ball, sphere, in reference to the overall 
shape of the cyst. 


Diacnosis: A proximate cyst, subspherical to broadly ovoidal with a strong 
apical horn. The sutural crests are low, generally well defined, and reflect the 
tabulation 4’, 1a, 6”, 6c, 6’, ?Ipand 1’’”’”. Cingulum moderately narrow, helicoid, 
laevorotatory, dividing the theca unequally, the epitract being longer than the 
hypotract. The sulcus is broad. The surface of the shell is densely granular. A 
precingular archaeopyle, formed by loss of plate 3’’, is developed in some instances. 

HototyPe: I.G.S. slide PK.122, Sample WB 20, H.M. Geological Survey Borehole, 
Warlingham, Surrey at 2510 ft depth. Middle Kimmeridgian (Wheatleyensis Zone). 

PARATYPE: BM(NH) slide V.56345. Sample FN 236, from the White Stone 


Band, + m west of Freshwater Steps, Dorset. Middle Kimmeridgian (boundary 
of Pectinatus-Hudlestoni Zones). 


196 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


Fic. 5. Gonyaulacysta globtaa sp. nov. A. Holotype: left, in ventral view; right, in 
dorsal view. I.G.S. slide PK 122. x c.800. B. Paratype: showing the epitractal 
tabulation: left, in ventral view; right, in dorsal view. BM(NH) slide V.56345. x c.655. 


FROM ENGLAND, SCOTLAND AND FRANCE 197 


Dimensions: Holotype: overall length gou, breadth 68y, apical horn length Iry. 
Paratype: overall length g2u, breadth 75u, horn length 12u. Range of the observed 
specimens: overall length 85-92u, breadth 62~-75u, horn length 11-12u. (Four 
specimens were measured.) 


Description: The cyst is globular, relatively thin-walled. Four apical plates 
combine to form the slender horn. Plate 1’ is narrow and elongate, the other 
apical plates are approximately polygonal but with an apical prolongation. A single 
anterior intercalary plate is present and quite large, apical plate 4’ and precingular 
plates 5” and 6” being correspondingly reduced. The four other precingular plates 
are large. The cingular plates are poorly defined, but appear to number six. 

The hypotract is dome-shaped, composed of large reflected plates; plate 4’’ is 
the largest of all. Plate 1’” is greatly reduced; plates 5’” and 6’” are relatively small. 
The boundary between the plates Ip and 2’” was not confirmed. The single 
antapical plate, 1’’’”’, is also large. 

The sulcus is narrow in its anterior portion, broadening to contact with the 
cingulum and thenceforward remaining of constant breadth in its posterior portion. 
It is relatively short and extends to the antapex. 

In one specimen only, a precingular archaeopyle was seen, formed by loss of plate 
gee 
OBSERVED RANGE: Kimmeridgian (Wheatleyensis-Pectinatus Zones). 

REMARKS: This species is extremely infrequent: of four specimens encountered, 
the holotype and paratype only are moderately well preserved, the other two being 
folded, crushed and severely damaged. 

In its combination of overall morphology and tabulation G. globata differs from 
previously described species of Gonyaulacysta. The most closely similar species is 
G. nuciformis, but G. globata differs in having a relatively thin cyst wall and dis- 
similar ventral antapical tabulation. 


Gonyaulacysta longicornis (Downie, 1957) Sarjeant, 1969, emend. 
Plate 2, figure 6; Plate 4, figure 1; text-figure 6 


1957 Gonyaulax longicovnis Downie, 420, pl. 20, fig. 8; text-figs 2a—b; table 1. 
1962 G. longicornis Downie; G. & M. Deflandre, fiche 1830. 

1964 G. longicoynis Downie; Downie & Sarjeant, 115. 

1964 G. longicorynis Downie; Sarjeant, table 2. 

1964 G. longicoynis Downie; Eisenack, 371-2. 

1966 ©Gonyaulacysta longicornis (Downie); Sarjeant, nomen nudum, 131. 

1967b G. longicornis (Downie); Sarjeant, nomen nudum, table 1. 

1967b Gonyaulax longicorvnis Downie; Vozzhennikova, table 12. 

1969 Gonyaulacysta longicornis (Downie); Sarjeant, ro. 

1970 G. longicornis (Downie); Gitmez, table 4. 


EMENDED DIAGNOSIS: This species of Gonyaulacysta is characterized by a very 
long apical horn (not less than one-third of the whole length). Tabulation: 4’, 6”, 
6c, 6’”, Ip and 1”. Cingulum slightly helicoid, dividing the cyst unequally: the 
epitract being longer than the hypotract. On the sutures, short, roughly denticulate 


198 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


crests rise up. Precingular archaeopyle sometimes present and formed by loss of 
plate 3’. Surface of the shell coarsely granular. 


Ho.otyPe: C. Downie’s collection, Micropalaeontological Laboratory, University 
of Sheffield, KL 11.15; from the Upper Kimmeridge Clay of Norfolk, England. 


FIGURED SPECIMENS: I.G.S. slide PK.120, Sample WB 18, Kimmeridge Clay, 
H.M. Geological Survey Borehole, Warlingham, Surrey, at 2560 ft depth. Middle 
Kimmeridgian (Wheatleyensis Zone). 

BM(NH) slide V.56346(2). Sample LO 353, from the Littleworth Quarry, 
Oxfordshire. Upper Kimmeridgian (Pallasioides Zone). 


Dimensions: Holotype, as quoted by Downie: overall length 92u, breadth 58u, 
horn length 36y. 

Figured specimen from Warlingham Borehole: overall length 115, breadth 75y, 
horn length 46u. Figured specimen from Littleworth: overall length 125, breadth 
85u, horn length 4ou. 

Range of the specimens from England and France: overall length 80-155y, 
breadth 55-100p, horn length 25-60u. Measured specimens 34 in number. 


Fic. 6. Gonyaulacysta longicorvnis (Downie). Specimen: left, in ventral view; right, in 
dorsal view. BM(NH) slide V.56346 (2). x c.704. 


FROM ENGLAND, SCOTLAND AND FRANCE 199 


DescriPTion: The thin-walled shell is roughly polygonal in shape, with a long 
apical horn and conical hypotract. The apical horn, with its solid tip, is formed by 
four long apical plates; plate 1’ is elongate, the others are almost triangular. The 
apical plates, together with six precingular plates, make up the epitract; this is 
separated from the hypotract by a narrow cingulum and is always longer than the 
hypotract. Six cingular plates of variable size occupy the cingulum. The sulcus 
extends onto the epitract and hypotract, between the apex and the antapex. Six 
postcingular plates of variable shape and size are present: plate 1’ is reduced to 
accommodate the posterior intercalary plate, Ip; plates 2’, 3’ and 5’’’ are more or 
less uniform in size and plate 4’” is the largest of all the plates. 


OBSERVED RANGE: Kimmeridgian (Baylei to Pallasioides Zones) [See discussion 
below]. 


TOTAL KNOWN RANGE: Kimmeridgian (Baylei to Pallasioides Zones). 


REMARKS: G. longicornis has been known hitherto only from the Upper Kim- 
meridgian of England. Though the specimens in the French and English assem- 
blages were generally badly preserved, it was possible to determine the tabulation 
and the mode of archaeopyle formation. This species was doubtfully included in the 
genus Gonyaulacysta by Sarjeant (1969), in the absence of knowledge of the type of 
archaeopyle; the new observations confirm this reallocation. 

The observed specimens are closely similar to Downie’s figured specimen, but show 
slight differences in tabulation. The apical horn is not developed from plate 1’ 
only, as figured by Downie; instead, it is made up of four apical plates. The posterior 
intercalary plate was not shown on the figure of the holotype, but was observed in 
all specimens encountered. 

G. longicornis is similar to Pareodinia nuda (Downie) in the shape of the apical 
horn and general appearance; but no tabulation has been yet determined for P. nuda 
and an intercalary archaeopyle was considered by Sarjeant (1967a pp. 254) to be 
developed in the latter species. 

In England, G. Jongicornis was found in most horizons of the Kimmeridgian from 
Aulacostephanus to Pallasioides, but it was absent from the lowest zones and the 
Rotunda Zone. In France, in contrast, it was recorded only from the Baylei Zone. 
Thirteen specimens from France and forty-six specimens from England were recorded. 


Gonyaulacysta cf. mamillifera (Deflandre, 1939b) Sarjeant, 1969 
Plate 4, figure 7; text-figure 7 


DESCRIPTION: Relatively large, globular shell, broadly ovoidal to subspherical in 
shape. The more or less equatorial cingulum is slightly helicoid and divides the 
cyst into two equal parts; the epitract terminates in a mammelon form (in two of 
the observed specimens, this was well-developed, but the third one has a feebly- 
developed apical prominence); the hypotract is rounded. Tabulation: 4’, 6’, 6c, 
6’, Ip, 1’’’.. Plate boundaries are marked by low membraneous crests. The 
sulcus is long, extending further on the epitract than on the hypotract; it narrows 


200 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


towards the apex. The shell wall is thin, its surface densely granular and punctate. 
A precingular archaeopyle is present, formed by the loss of plate 3”. 


FIGURED SPECIMEN: I.G.S. slide PK.130, Sample WB 29, from H.M. Geological 
Survey Borehole, Warlingham, Surrey, at 2285 ft 7in. depth. Upper Kimmeridgian 
(Rotunda Zone). 


DIMENSIONS: Figured specimen: length g2u, breath 80u. Range: length 76-92, 
breadth 60-80, measured specimens 3 in number. (Holotype dimensions: length 
g2u, breadth 84u, as given by Deflandre). 


REMARKS: G. mamullifera has only been previously recorded from the Kimmeridgian 
of France. In this investigation, three specimens probably attributable to this 
species were observed: one from the Baylei Zone of France and two from the Rotunda 
Zone of England. In their general aspect they are closely similar to G. mamuillifera ; 
however, there are differences in the reconstructed tabulation and the ornamentation 
ofthesutures. In the observed specimens the sutures are in the form of membraneous 
crests, not spinose, as described by Deflandre. The tabulation is generally similar, 
but the shapes of postcingular plates 1’’’ and 2’” are different. Comparison between 
the apical plates of this form and G. mamiutllifera was not possible, because Deflandre 
was unable to determine the apical tabulation. Allocation to this species must, 
therefore, be provisional only. 


Gonyaulacysta nuciformis (Deflandre) Sarjeant, 1969 
Plate 3, figure 5; text-figure 8 


1938 Palaeoperidinium nuciforme Deflandre, 180, pl. 8, figs 4-6. 

1962a P. nuciforme Deflandre; Sarjeant, pl. 1, fig. 8; tables 3-4. 

1962b Gonyaulax nuciformis (Deflandre); Sarjeant, 482-3, pl. 69, fig. 6; text-fig. 4; tables 2-3. 
1964 G. nuciforymis (Deflandre); Downie & Sarjeant, 115. 

1964 G. nuciformis (Deflandre); Sarjeant, table 2. 

1964 Palaeoperidinium nucifornis Deflandre; Eisenack, 609. 

1965 Palaeoperidinium nuciformoides Gorka, 300-1, pl. 2, figs 1-2; table 1. 

1966 P. nuciforymoides (Deflandre) G. & M. Deflandre, fiche 3030. 

1966 ?Gonyaulacysta nuciformis (Deflandre); Sarjeant, nomen nudum 132. 

1967b Gonyaulax nuciformis (Deflandre) ; Vozzhennikova, table 11. 

1967b Gonyaulacysta nuciformis (Deflandre); Sarjeant, nomen nudwm, table tr. 

1968b G. nuciformis (Deflandre); Sarjeant, nomen nudum, 227, pl. 3, fig. 4; table 2A. 
1969 G. nuciformis (Deflandre); Beju, nomen nudum, to, pl. 3, fig. 1; table 1. 

1969 G. nuciformis (Deflandre) ; Sarjeant, Io. 

1970 G. nuciformis (Deflandre) ; Gitmez, 3, pl. 6, fig. 1; table 4. 


DESCRIPTION: The shell is ovoidal to spherical, with the tabulation 4’, Ia, 6”, 
6c, 6’’, Ip, Ipv and 1’’’. The epitract and hypotract are more or less equal in size; 
the epitract ends with an apical horn of variable length, the hypotract is dome- 
shaped with rounded antapex. The cingulum is helicoid, laevorotatory. The 
sulcus is broad and extends onto both the epitract and hypotract. The shell is 
densely granular and relatively thick; because of this, determination of the tabula- 
tion is difficult. A precingular archaeopyle was developed by some specimens, 
formed by loss of plate 3”. 


FROM ENGLAND, SCOTLAND AND FRANCE 201 


Fic. 7. Gonyaulacysta cf. mamillifera (Deflandre). Showing the tabulation: left, in ventral 
view; right, in dorsal view. I.G.S. slide PK 130. X c.772. 


Fic. 8. Gonyaulacysta nuciformis (Deflandre). Tabulation: left, in ventral view; right, in 
dorsal view. Specimen I.G.S. slide PK tog. x c.1112. 


202 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


FIGURED SPECIMEN: I.G.S. slide PK.109, Sample WB 7, from H.M. Geological 
Survey Borehole, Warlingham, Surrey, at 2834 ft 7in. depth. Lower Kimmeridgian 
(Eudoxus Zone). 

DIMENSIONS: Figured specimen: overall length 7ou, breadth 60u, horn length 
Ou. 

Range of the Lower Kimmeridgian specimens (61 specimens were measured): 
overall length 43-118p, breadth 40-85y, horn length 4-12y. 

Range of the Middle Kimmeridgian specimens (28 specimens were measured): 
overall length 68—-105y, breadth 60-85y, horn length 5-12y. 

Range of the Upper Kimmeridgian specimens (18 specimens were measured): 
overall length 65—102p, breadth 55-85, horn length 6—-12u. 

The following dimensions were quoted by Deflandre for the Oxfordian specimens 
from France: overall length 60-65u,, breadth 47-53 (approximately). Dimensions 
of the Callovian specimens from England, as given by Sarjeant: overall length 56-58y, 
breadth 50-64u. Gorka gave the following dimensions for Polish Upper Jurassic 
specimens: overall length 38-54y, breadth 40-44u. Dimensions of the Roumanian 
specimens (Oxfordian to Kimmeridgian) are given by Beju as overall length 62—78y, 
breadth 60-78u. The Polish specimens are thus smaller than the others and the 
Roumanian specimens are more spherical. The Kimmeridgian specimens are larger 
than the specimens from lower stages. 


OBSERVED RANGE: Kimmeridgian (Baylei to Pallasioides). 


TOTAL KNOWN RANGE: Upper Callovian (Lamberti) to Upper Kimmeridgian 
(Pallasioides). 


REMARKS: G. nuciformus was first recorded from the Upper Jurassic of France by 
Deflandre (1938). Subsequently, this Upper Jurassic species has been observed in 
several assemblages from Western Europe, and the geographic range has been 
extended by its observation from the Callovian to Kimmeridgian of Roumania by 
Beju (1969). It is generally present in moderate abundance in Kimmeridgian 
assemblages; however, it was not observed in the Middle and Upper Kimmeridgian 
of France. Also there is a progressive reduction in the number of specimens in the 
English assemblages through the Upper Kimmeridgian. 

The combination Gonyaulacysta nuciformis in Beju (1969), although proposed in 
correct form, was not validly published since a pre-print distributed at a meeting 
does not constitute effective publication (cf. ‘International Code of Botanical 
Nomenclature’, Art. 29). The combination is, therefore, correctly attributed to 
Sarjeant (1969). 


Gonyaulacysta perforans (Cookson & Eisenack) Sarjeant, 1969 
Plate 4, figure 6; text-figure 9 


1958 Gonyaulax perforans Cookson & Eisenack, 30, pl. 2, figs 1-4, 7-8; text-figs 8-9. 
1961 G. perfovans Cookson & Eisenack; Alberti, 6, pl. 11, figs 4-6; tables a—c. 

1962 G. perfovans Cookson & Eisenack; G. & M. Deflandre, fiches 1849-1852. 

1963 G. perforans Cookson & Eisenack; Baltes, 584, pl. 4, figs 1-6, table 1. 

1964 G. perfovans Cookson & Eisenack; Downie & Sarjeant, 115. 


FROM ENGLAND, SCOTLAND AND FRANCE 203 


1964 G. perfovans Cookson & Eisenack; Sarjeant, table 2. 

1964 G. perforans Cookson & Eisenack; Eisenack, 397-8. 

1965 G. perforans Cookson & Eisenack; Baltes, 12, pl. 3, figs 93-4. 

1966 Gonyaulacysta perforans (Cookson & Eisenack); Sarjeant, nomen nudum, 131. 
1967b Gonyaulax perforans Cookson & Eisenack; Vozzhennikova, table 12. 

1967 G. perforans Cookson & Eisenack; Millioud, pl. 2, fig. 15; text-fig. I. 

1969 G. perforans Cookson & Eisenack; Baltes, fig. 3. 

1969 Gonyaulacysta perforans (Cookson & Eisenack) ; Sarjeant, Io. 


DescRIPTION: The cyst is elongate, with a long apical horn. The epitract and 
hypotract are separated by the helicoid, laevorotatory cingulum and are more or 
less equal in size. Rabulation: 44, 64,0, ip,and«1 "4 Plate boundaries are 
demarcated by membraneous, delicate porate crests, which are well developed 
around the apex and the antapex. The sulcus is long and narrow, extending from 
apex to antapex. The shell wall is thin, the surface granular and occasionally 
perforate. An archaeopyle was rarely observed; when developed, it forms by the 
loss of plate 3”. 


Fic. 9. Gonyaulacysta perforans (Cookson & Eisenack). Tabulation: left, in ventral view; 
right, in dorsal view. I.G.S. slide PK 131. X c.1491. 


204 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


FIGURED SPECIMEN: I.G.S. slide PK.131, Sample WB 29, from H.M. Geological 
Survey Borehole, Warlingham, Surrey, at 2285 ft 7 in. depth. Upper Kim- 
meridgian (Rotunda Zone). 


DIMENSIONS: Figured specimen: overall length 108, breadth 7ou, horn length 33u. 
Range of the Middle Kimmeridgian specimens (7 specimens measured): overall 
length 73-100n, breadth 54-73u, horn length 16-18y. 15 specimens measured 
from the Upper Kimmeridgian: overall length 80—110y, breadth 52-75, horn length 
12-40u. Cookson and Eisenack gave the following dimensions for the specimens 
from New Guinea: length 136-168y, breadth 93-109gy. Dimensions of the specimens 
from Germany are quoted by Alberti as length 130-145y and breath 81-103u. The 
British and French Middle Kimmeridgian specimens are thus smaller than the 
Upper Kimmeridgian specimens, but both are smaller than the New Guinea and 
German specimens. 


OBSERVED RANGE: Kimmeridgian (Wheatleyensis to Pallasioides). 
TOTAL KNOWN RANGE: Upper Jurassic to Lower Cretaceous (Albian). 


REMARKS: G. pervforans was originally recorded from the Upper Jurassic of New 
Guinea by Cookson and Eisenack; later Alberti observed it in the Barremian assem- 
blages from Germany and Baltes recorded it from the Albian of Roumania. It is 
recorded in English assemblages for the first time. The observed specimens are 
similar to those figured by Cookson and Eisenack, except for small differences in 
tabulation and in the length of the apical horn. 

Although the New Guinea and German specimens are larger than the Kimmeridgian 
specimens, from the figures they seem to have a proportionately smaller horn. 
(Since the horn length was not specified, it is possible to deduce this only from the 
figures.) 

Cookson and Eisenack did not mention the presence of apical plate 4’, but in 
their figure a boundary is shown between the plates 3’ on the ventral side and 3’ 
on the dorsal side; therefore, the plate on the ventral side should be the fourth apical 
plate, as observed in the Kimmeridgian specimens. Similarly the elongate plate 
which they figure below the postcingular plate 1’’’ should be the posterior inter- 
calary plate, Ip. 


Gonyaulacysta systremmatos sp. nov. 
Plate 5, figures 7-8 

1970 Gonyaulacysta sp. C. Gitmez, 265-7, pl. 4, figures 10-11, text-fig. 15, table 4. 

DERIVATION OF NAME: Greek, systremmatos, anything consolidated, generally a 
ball or round object; in reference to the ball-like shape of the shell. 

DiaGnosis: Thick-walled shell, almost spherical, with a moderately long apical 
horn. Tabulation: 4’, 1a, 6”, 6-7c, 7’”, Ip, Ipv, 1’. The plate boundaries are 
demarcated by delicate crests of variable height. The cingulum is helicoid, laevoro- 


tatory; the sulcus is short and broadens posteriorly. The surface is densely granular. 
A precingular archeopyle, formed by loss of plate 3’’, is generally developed. 


FROM ENGLAND, SCOTLAND AND FRANCE 205 


HoLotyPre: BM(NH) slide V.53966(z), from the sample CC 447, Argiles de Moulin 
Wibert, Cap de la Créche, Boulonnais, France. Lower Kimmeridgian (Baylei 
Zone). 


Dimensions: Holotype: overall length 68u, breath 62, horn length 8y, height of 
the crests 4-5u. Range of the observed specimens: overall length 66-78, breadth 
60-65, horn length 7-16; measured specimens 5 in number. 


Description: The helicoid, laevorotatory cingulum divides the cyst unequally. 
The epitract is somewhat longer than the hypotract; both are more or less dome- 
shaped. The number of the cingular plates is hesitantly mentioned, because the 
character of the small plate beside 6c is doubtful; it may be either a small cingular 
plate or a short sulcal plate. 

Four apical plates make up the apex, plate 1’ occupying the anterior prolongation 
of the sulcus. Plates 2’ and 3’ are small; plate 4’ is almost as large as plate 1’. The 
single, small anterior intercalary plate is placed between the plates 4’ and 6’. The 
precingular plates are generally large, plate 6’’ being of reduced size because of the 
presence of intercalary plate Ia. 

The postcingular plates are of variable size and shape: plate 1’ is very small; 
plate 2’” is also reduced and does not have a boundary with the antapical plate. 
Plates 3’”, 4”, 5’” and 6’” are relatively large; plate 7’” is in contrast reduced, 
having nearly the same size as plate 2’”. The quite broad intercalary plate, Ipv, 
separates the sulcus from the single antapical plate 1’’””’. 


4st 


REMARKS: This is an infrequent species, six specimens being encountered, all 
from the Baylei Zone of France. They were badly preserved, being somewhat 
crushed, folded or covered by debris; the holotype was the best oriented for study. 
In its general form, this new species of Gonyaulacysta differs from all described 
species. The most closely comparable species is G. palla Sarjeant, which has a 
similarly spherical shape and comparable tabulation; but G. systemmatos differs in 
its apical horn, sutural crests, absence of plate 1a, and presence of plate Ipv. In the 
possession of a seventh postcingular plate, it is comparable with G. fetchamensis and 
G. ehrenbergi1, but it is markedly different in overall morphology from both these 
species. 


Gonyaulacysta sp. A 
Plate 9, figures 1-2 
1970 Gonyaulacysta sp. A. Gitmez, 263-4, pl. 3, fig. 3, text-fig. 13. 


FIGURED SPECIMEN: BM(NH) slide V.56347(2), Kimmeridge Clay (Pectinatus 
Zone) 60 ft above Freshwater Steps Stone Band, Egmont Bight, Dorset. 

DIMENSIONS: Figured specimen: overall length 103u, length of apical horn 32u, 
overall breadth 66-5u, length of crest spines c. 1:5—2u. 

RemaARKS: This form was originally described on the basis of two specimens from 
the lowest Kimmeridge Clay (Baylei Zone) of Normandy. The discovery of a third 
specimen at a higher horizon is thus of interest: its dimensions are markedly larger 


206 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


than those of the specimens described earlier (overall length 65u, breadth 42y) but 
its proportions are similar. Yet further specimens of this type must be located 
before nomenclatural proposals can justly be made. 


Gonyaulacysta sp. B 
Plate 4, figures 2-3, text-figure 10 


DESCRIPTION: Only one specimen of this species has so far been observed. It 
possesses a subspherical cyst, bearing a moderately well developed apical horn. 
The strongly helicoid, laevorotatory cingulum divides the cyst into two more or 
less equal parts: the hypotract is somewhat flattened at the antapex. The sulcus is 
sigmoidal and narrow. Tabulation: 4’, 6’, 6c, 5’, Ip, ?Ipv and 1’’”. 

The apical plates 1’ and 4’ are small and elongate; together with plates 2’ and 3’, 
they form the apical horn. The precingular plates are quite large. Plate 3” is 
lost in archaeopyle formation. On the hypotract, crests demarcate five postciagular 
plates. Plate 1’ and 5’” are reduced because of the presence of posterior plates, 
but the other postcingular plates are large. A single antapical plate occupies the 
antapex. 

The wall is moderately thin, its surface finely granular and in part tuberculate. 
Crests on the plate boundaries are delicate; the denticulation is very deep, virtually 
giving the crests the appearance of a row of bifid spines. 

FIGURED SPECIMEN: I.G.S. slide PK.117, Slide WB15, from H.M. Geological 
Survey Borehole, Warlingham, Surrey, at 2635 ft 3ia. depth. Middle Kimmeridgian 
(Elegans Zone). 


Fic. 10. Gonyaulacysta sp. B. Tabulation: left, in ventral view; right in dorsal view. 
Specimen I.G.S. slide PK 117. X ¢.1351. 


FROM ENGLAND, SCOTLAND AND FRANCE 207 


DIMENSIONS: Overall length 48y, breadth 45u, horn length 5u, sutures 3-5. high. 


RemARKS: In its general morphological features and sutural characteristics, this 
species may be distinguished from all previously described species of Gonyaulacysta. 
The shape of the shell and crests is most comparable to G. serrata Cookson & Eisenack 
(1958) suggesting a relationship between the two species, but the form of the apical 
horn is different ; since a tabulation could not be determined for G. serrata, a detailed 
comparison of these two species is impossible. 


Gonyaulacysta sp. C 
Plate 6, figures 1-2, text-figure I1 


Description: The cyst is subspherical, bearing a short, tapering apical horn. 
The thickness of the wall is uneven because of irregularly distributed granules. The 
sutural crests are in the form of low ridges giving rise occasionally to delicate mem- 
branes: they indicate a reflected tabulation of 4’, Ia, 6’’, 6c, 6’’’, ?>Ipv, 1'’’’.. Four 
apical plates together form the horn; plate 1’ is elongate in shape. The precingular 
plates, except plate 6’’, are of almost uniform shape and size; plate 6’’ is reduced 
to accommodate the intercalary plate fa. 

Six cingular plates make up the slightly helicoid, laevorotatory cingulum: plate 6c 
is very small, the others are relatively large. The ends of the cingulum are widely 
separated by a very broad sulcus, which further widens in its posterior portion. 


Fic. 11. Gonyaulacysta sp. C. Tabulation: left, in ventral view; right, in dorsal view. 
Specimen I.G.S. side PK 118.  c.984. 


208 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


(The antapical end of the sulcus and the plate boundaries near to the antapex were 
not very clear because of bad preservation of this part of the cyst.) The first post- 
cingular plate, 1’, is narrow, elongate and small. Plate 4’’’ appears the largest of 
the post-cingular plates. No archaeopyle was observed in this specimen. 


FIGURED SPECIMEN: I.G.S. slide PK.118, Sample WB 16, from H.M. Geological 
Survey Borehole, Warlingham, Surrey, at 2510 ft depth. Middle Kimmeridgian 
(Scitulus Zone). 


DIMENSIONS: Overall length 77u, breadth 60, apical horn length 8y. 


REMARKS: Only one specimen has so far been observed. It is distinguished from 
all previously described species in its overall morphological features; it is possibly 
a new species, but further specimens are needed to decide this. 


Gonyaulacysta sp. D 
Plate 6, figures 4-5; text-figure 12 


DeEscripTION: A specimen with an almost spherical cyst and short, blunt, 
tapering apical horn. The shell wall is composed of two layers, periphragm and 
endophragm, which are of the same thickness; the periphragm is coarsely granular. 
The apical horn is formed of both shell layers. Tabulation: 4’, 1a, 6”, 6c, 6’, Ip 
and 1’’’”. Plate 1’ is elongate and occupies the anterior prolongation of the sulcus. 
Plates 2’ and 3’ are large; plate 4’ is slightly reduced to accommodate the anterior 
intercalary plate, Ia. Four apical plates together make up the apical horn. Plate 
Ia is quite large; because of this, plate 6’ is reduced. The other precingular plates 
are of more or less similar shape and size. The cingulum is of moderate breath, 


Fic. 12. Gonyaulacystasp.D. Tabulation and archaeopyle formation, Plate 3” is partially 
lost in the archaeopyle formation. Specimen BM(NH) slide V.56346 (4). c.1035. 


FROM ENGLAND, SCOTLAND AND FRANCE 209 


possessing six cingular plates: plate 1c is smaller and broader than the other cingular 
plates. Postcingular plate 1’” is very small and gives the appearance of hanging 
onto one corner of the cingulum. Plate 2’” and 6’” are relatively small; plates 3’”, 
4’” and 5’” are large. An elongate posterior intercalary plate (Ip) is placed below 
plate r’’’. The single antapical plate, 1’’’’, is large and convex. The broad sulcus 
extends between the apex and antapex. 

Plate boundaries are demarcated by low crests and generally well defined. A 
precingular archaeopyle was seen in some specimens; it forms by loss of plate 3” 
(in the figured specimen, plate 3” is partially detached). 


FIGURED SPECIMEN: BM(NH) slide V.56346(4). Sample LO 353, from the 
Littleworth Quarry, Oxfordshire. Upper Kimmeridgian (Pallasioides Zone). 


DIMENSIONS: Figured specimen: overall length 65u, breadth 60, horn length 5y. 
Range: overall length 65—80u, breadth 60-75y, horn length 4-7. Measured speci- 
mens 5 in number; 3 other observed specimens could not be measured because of bad 
preservation. 


REMARKS: This unnamed species of Gonyaulacysta differs from all described 
species in its general aspect and peculiar apical horn. The most comparable species 
is G. palla Sarjeant, both species having similarly spherical cysts and tapering 
apical horns. In Gonyaulacysta sp. C, the apical horn is broad based and short and 
its tip appears conical: although G. palla has a tapering horn, it is slender and 
relatively long. The number of the plates on the epitract is the same for both species, 
but plate 4’ is not placed at the top of the horn as in G. palla. The hypotractal 
plates (especially plates 1’’’, 2’”’ and 1p) appear similar in shape to those of G. palla, 
but their number is different: G. palla has seven postcingular plates, whereas this 
species has six. The crests of G. palla are spiny. The similarity between these two 
species is thus only in the overall shape. 

Eight specimens, all from the same quarry in Littleworth, were recorded; un- 
fortunately, all the specimens encountered are somewhat crushed, folded or covered 
by debris, which makes them difficult to examine in detail. The figured specimen 
was the best oriented for study. It may be a new species, but needs further, better 
preserved specimens for typification. 


Gonyaulacysta sp. E 
Plate 6, figure 9; text-figure 13 


DESCRIPTION: Only one moderately well preserved specimen of this type was 
observed, in the Lower Kimmeridgian assemblages from the Warlingham Borehole. 
It possesses an elongate cyst, with conical epitract and dome-shaped hypotract, thus 
looking rather like a pear. The apical horn is slender and tapering. The wall is 
densely granular. Plate boundaries are well defined by moderately high membraneous 
crests. Tabulation: 4’, 1a, 6”, 6c, 6’’, Ip, Ipv and 1’. Plate 1’ is characteristi- 
cally long and broad, extending down almost two-thirds of the epitract. Plates 2’ 
and 3’ are similar to each other; plate 4’ is greatly reduced because of the anterior 
intercalary plate 1a. For the same reason, plates 5’ and 6” are also reduced. 


210 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


The other precingular plates are quite large. The six postcingular plates are of 
variable shape and size. Plate 1’’’ is small and triangular; plates 2’ and 6’” are 
moderately large; plates 3’, 4’ and 5’” very large, together almost occupying the 
whole dorsal side of the hypotract. A single plate occupies the antapex. The 
posterior intercalary plate (Ip) is elongate. A crescent-shaped plate, Ipv, separates 
the sulcus from the antapical plate 1’’’. The cingulum is deep, formed by 6 
cingular plates, of which 5c and 6c are quite small; it is almost circular and divides 
the cyst into two unequal parts, with the epitract twice as long as the hypotract. 
The sulcus is very short and broad. An archaeopyle was not observed. 


FIGURED SPECIMEN: I.G.S. slide PK.1113. Sample WB 13, from H.M. Geological 
Survey Borehole, Warlingham, Surrey, at 2684 ft 3in. depth. Lower Kimmeridgian 
(Autissiodorensis Zone). 

DIMENSIONS: Figured specimen: overall length 65u, breadth 5ou, apical horn 
length 7-5u. 

REMARKS: The long epitract, densely granular shell wall, elongate apical plate 1’ 
and large postcingular plates 4’ and 5’” distinguish this form from all described 
species. It almost certainly represents an undescribed species of Gonyaulacysta, 
but before this can be decided, more specimens must be awaited. 


Fic. 13. Gonyaulacysta sp. E. Tabulation: left, in ventral view; right in dorsal view. 
Specimen I1.G.S. slide PK 113. X c.669. 


FROM ENGLAND, SCOTLAND AND FRANCE Ziit 


Gonyaulacysta sp. F. 
Plate 6, figures 3, 6; text-figure 14 


DescripTION: The cyst is elongate, with a long and tapering apical horn. The 
cyst wall is composed of two layers; a fairly thin endophragm and a thicker peri- 
phragm. The endophragm bulges into the lower half of the apical horn; the anterior 
portion of the horn is formed by the periphragm only, so that there is a cavity 
between the wall layers at the anterior end of the horn. Tabulation: 4’, 1a, 6”, 
6c, 6’’, Ip, Ipv and 1’. The four apical plates together make up the apical horn. 
Plate 1’ is elongate, extending down two-thirds of the epitract. The anterior 
intercalary plate (1a) is quite large: because of this, precingular plate 6’’ is reduced. 
The other precingular plates are relatively large. The postcingular plates 1’’’ and 
6'’’ are small, the others are moderately large. The posterior intercalary plate (1p) 
is elongate: the boundary between the sulcus and the posterior ventral plate (1pv) 
was not confirmed. A single narrow plate occupies the antapex. 

The cingulum is strongly helicoid, laevorotatory, dividing the cyst unequally, 
the epitract being longer than the hypotract. The sulcus is broad and largely con- 
fined to the hypotract. 


Fic. 14. Gonyaulacysta sp. F. Tabulation and archaeopyle formation (the operculum 
has partially slipped inside the cyst). Left, in ventral view; right, in dorsal view. 
Specimen BM(NH) slide V.56348 (1). c.983. 


212 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


The plate boundaries are marked by crests in the form of very low, thick mem- 
branes. The surface of the shell is densely granular. A precingular archaeopyle 
forms by loss of plate 3’’; on the figured specimen, the operculum is partially slipped 
inside. 

FIGURED SPECIMEN: BM(NH) slide V.56348(1). Sample ED 240, from 30 ft 
above Freshwater Steps Stone Band, Egmont Bight, Dorset. Upper Kimmeridgian 
(Pectinatus Zone). 


DIMENSIONS: Figured specimen: overall length 92y, breadth 52u, apical horn 
length 26. 


REMARKS: The description of this species was based on a single specimen observed 
in the assemblages examined. In its overall morphology it is typically a species of 
Gonyaulacysta, but it is markedly different from all previously described species. It 
may be compared with G. perforans, since both have a similarly elongate theca, with 
long apical horn, and a comparable tabulation, but the crests on the sutures are 
completely different: G. perforans has well developed, porate membraneous crests, 
whereas this form has low, thick membraneous crests. G. perforans apparently has 
a single-layered wall, but in this species the shell wall is distinctly two layered. This 
specimen certainly represents a new species of Gonyaulacysta but, since the only 
specimen observed is not well preserved, no new name is given. 


Gonyaulacysta sp. G 
Plate 6, figures 7-8; text-figure 15 


DEscRIPTION: The cyst is broadly ovoidal, with a strong apical horn. Tabulation: 
4’, 6”, 6c, 6’”, Ip, ?Ipv and 1’’’. The apical plates 1’ and 4’ are broad and long, 
plates 2’ and 3’ are rounded, smaller. The precingular plates are moderately large, 
except for plates 1’ and 6” which are somewhat smaller than the others. Plate 3’ 
is typically lost in archaeopyle formation. The postcingular plates 1’”, 5’ and 
6’” are small; in contrast, plates 3’” and 4’” are very large and occupy almost the 
whole dorsal side of the hypotract. The single antapical plate, 1’’’”’, is quite large 
and convex; plate Ip is small. On the posterior portion of the sulcus some small 
plates were suggested, but their presence could not be confirmed: they may constitute 
a subdivided posterior ventral plate Ipv. 

The cingulum is narrow, helicoid, laevorotatory, comprised of six cingular plates. 
It divides the cyst unequally into two parts, the epitract being smaller than the 
hypotract. The sulcus is short, mainly confined to the hypotract and broadening 
posteriorly. 

The plate boundaries are marked by high, delicate crests, which have smooth 
edges and are irregularly perforate. The surface of the shell is densely granular. 
The dense granulation and high crests render the tabulation difficult to determine. 


FIGURED SPECIMEN: BM(NH) slide V.56349(1). Sample HC 243, from c. roo ft 
below the Rotunda Nodules, in the base of Hounstout Cliff, Dorset. Upper 
Kimmeridgian (Pectinatus Zone). 


FROM ENGLAND, SCOTLAND AND FRANCE 213 


Fic. 15. Gonyaulacystasp.G. Tabulation and archaeopyle formation (plate 3” is missing). 
Left, in ventral view; right, in dorsal view. Specimen BM(NH) slide V.56349 (1). 
X €.1024. 


Dimensions: Figured specimen: overall length 75u, breadth 45u, apical horn 
length tou, breadth of the cingulum 5y. 


REMARKS: This single specimen differs from the described species of Gonyaulacysta 
in its general shape and distinctive sutural crests. The tabulation and perforate 
crests are similar to those in G. perforans, but in the other morphological characters 
those species are dissimilar. 


Gonyaulacysta sp. H 
Plate 13, figure 1, text-figure 16 


DEscrIPTION: Cyst subpolygonal to ovoidal, with a strong apical horn of moderate 
length. The cyst wall is rather thick and composed of two layers, the periphragm 
alone forming the horn; the surface of the periphragm is densely and finely granular 
Tabulation 4-?5’, 1a, 6’, 6c, 5’, op, ?Ipv, 1’. The sutures are indicated by low 
ridges, from which arise small prominences, too blunt and short to be called spines. 
The number of apical plates is doubtful only because a small circular plate appears 
to cap the horn: four other plates can clearly be seen, plate 1’ being unusually large 
and broad. Plate 6” of the precingular series is reduced to accommodate an 
obliquely positioned anterior intercalary plate: plate 3” is lost in archaeopyle 
formation. 


214 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


The cingulum is narrow and pronouncedly laevorotatory, its two ends differing 
in antero-posterior position by three times its breadth. The sulcus is broad: it is 
widely separated from the apex by the enlarged plate 1’, from the antapex (apparent- 
ly) by a narrow posterior ventral plate, whose boundary was only doubtfully 
determined. 

Only five postcingular plates appear to be present, the first being reduced: no 
posterior intercalary plate was determinable. The single antapical plate is relatively 
small. 


FIGURED SPECIMEN: BM(NH) slide V.56339(1). Sample CH 231, Kimmeridge 
Clay (Wheatleyensis Zone) 22 ft below the Blackstone, Clavells Hard, Dorset. 


DIMENSIONS: Figured specimen; overall length 120u, length of apical horn 30, 
breadth 72-5u, crests c. I-5u high. 


REMARKS: This single specimen certainly represents an undescribed species of 
Gonyaulacysta, characterized by its shape and tabulation. In general proportions, 
it is akin to a number of other Upper Jurassic and Lower Cretaceous species, all of 
which, however, have more elaborate crests and a more complex tabulation. 


Fic. 16. Gonyaulacystasp.H. Tabulation and archaeopyle formation (plate 3” is missing). 
Left, in oblique ventral view; right, in oblique dorsal view. Specimen BM(NH) slide 
V.56339 (1). X c.640. 


FROM ENGLAND, SCOTLAND AND FRANCE 215 


Genus LEPTODINIUM Klement, 1960b emend. Sarjeant, 1969 
Leptodinium aceras (Eisenack) Sarjeant, 1969, emend. 
Plate 5, figures 1-3, text-figure 17 


1958 Gonyaulax aceras Eisenack, 391, pl. 2, figs 1-2. 

1962 G. acevas Eisenack; G. & M. Deflandre, fiche 1752. 

1964 G. acevas Eisenack; Downie and Sarjeant, 113. 

1964 G. acevas Eisenack; Eisenack, 311. 

1966 ?Gonyaulacysta aceyas (Eisenack); Sarjeant, nomen nudum, 131. 
1967b G. acevas (Eisenack); Sarjeant, nomen nudum, table t. 

1967b Gonyaulax acevas Eisenack; Vozzhennikova, table II. 

1969 Leptodinium aceras (Eisenack); Sarjeant, 12. 


EMENDED DIAGNOSIS: Cyst broadly ovoidal to subspherical, without appendages, 
with tabulation 4’, 1a, 6’, 6c, 6’”, Ip, ipvand 1’. Cingulum helicoid, laevorotatory ; 
sulcus narrow, extending on both epitract and hypotract. Sutures in the form of 
low membraneous crests. Surface coarsely granular. Archaeopyle rarely developed, 
formed by loss of plate 3’’. 

HototyPe: Tubingen, Geol.-Palaont. Institut, Pr. 1125, Ob. Apt. Nr.g. Aptian, 
North Germany. 

FIGURED SPECIMENS: I.G.S. slide PK.108. Sample WB 7, from H.M. Geological 
Survey Borehole, Warlingham, Surrey, at 2834 ft 7in. depth. Lower Kimmeridgian 
(Eudoxus Zone). 


Fic. 17. Leptodinium acevas (Eisenack). Tabulation: left, in ventral view; right, in 
dorsal view. I.G.S. slide PK 108. X c.1041. 


216 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


I.G.S. slide PK.112. Sample WB 13, from the Warlingham Borehole, at 2684 ft 
3 in. depth. Lower Kimmeridgian (Autissiodorensis Zone). 


DIMENSIONS: Holotype: overall length 85u, breadth 71u. Range of the observed 
specimens, which are 16 in number; overall length 60-95y, breadth 52—90u. 


DEscRIPTION: The moderately thick-walled cyst is divided into two unequal 
parts by the relatively narrow cingulum. The epitract is slightly longer than the 
hypotract: both are dome-shaped. 

Four apical plates, of variable shape and size, make up the apex: plate 1’ is 
elongate and sigmoidal, almost as long as the sulcus, and extending down two-thirds 
of the epitract. Plates 2’ and 3’ are quite large; plate 4’ is reduced because of the 
larger anterior intercalary plate (Ia), which is also the reason for the reduction of 
precingular plate 6’. The other precingular plates are relatively large. The 
cingular plates are narrow and long, plate 1c being smallest. Six postcingular plates 
are present, with plate 1’ reduced and triangular. Plate 4’’’ is the largest plate of the 
cyst. The intercalary plate (1p) is placed below the plate 1’”, its outbulge causing 
the sulcus to become narrower. A quite large plate, Ipv, separates the single 
antapical plate 1’’” from the sulcus and plate Ip. 


OBSERVED RANGE: Kimmeridgian (Autissiodorensis to Pectinatus). 


TOTAL KNOWN RANGE: Kimmeridgian (Autissiodorensis to Pectinatus) and 
Aptian. 

REMARKS: The diagnosis is emended to include reference to the tabulation and the 
mode of archaeopyle formation. (In his original diagnosis, Eisenack was unable to 
give the tabulation pattern.) Sixteen specimens were observed in the Kimmeridgian 
assemblages from England: although they were not perfectly preserved, it was 
possible to determine the tabulation, one of them (the figured specimen) showing 
it particularly well. A precingular archaeopyle was observed in only two of the 
specimens; an archaeopyle of this type is figured by Eisenack, who recorded this 
species from the Aptian of Germany and placed it in Gonyaulax. Since it has no 
apical horn it was transferred to the genus Leptodinium by Sarjeant (1969). 


Leptodinium amabilis (Deflandre) Sarjeant, 1969 
Plate ro, figures 5-6, text-figure 18 


1939b Gonyaulax amabilis Deflandre, 143, pl. 6, fig. 8. 

1941b G. amabilis Deflandre; Deflandre, 11, pl. 3, figs 8-9, text-figs 1-2. 
1962 G. amabilis Deflandre; G. & M. Deflandre, fiche 1755. 

1964 G. amabilis Deflandre; Downie and Sarjeant, 113. 

1964 G. amabilis Deflandre; Eisenack, 315-316. 

1964 G. amabilis Deflandre; Sarjeant, table 2. 

1966 Gonyaulacysta amabilis (Deflandre); Sarjeant, nomen nudum, 130. 
1967b G. amabilis (Deflandre) ; Sarjeant, nomen nudum, table 1. 

1967b Gonyaulax amabilis Deflandre; Vozzhennikova, 91, table 11. 
1969 Leptodinium amabilis (Deflandre) ; Sarjeant, 12. 

1970 L. amabilis (Deflandre) ; Gitmez, 269-70, pl. 12, figs 1-2. 


FROM ENGLAND, SCOTLAND AND FRANCE 217 


DeEscriPTIoNn: The cyst is broadly ovoidal, with the tabulation 4’, 6”, 6c, 6’”, 
Ip, Ipv, 1’. The strongly spiral cingulum divides the cyst more or less equally. 
The sulcus is long and extends onto both epitract and hypotract, being narrow on the 
epitract. Moderately high crests arise from the sutures, distally feebly denticulate 
or smooth. The surface of the shell is smooth or finely granular. A precingular 
archaeopyle is sometimes developed, by loss of plate 3”. 


FIGURED SPECIMEN: BM(NH) slide V.56350(1)._ Sample OF 485, from the road 
side, Montard d’Oignon, France. Lower Kimmeridgian (Mutabilis Zone). 


Dimensions: Figured specimen: overall length 38u, breadth 34u. Range of the 
observed specimens (8 in number): length 38-5o0u, breadth 34—45u, sutures length 
3-4u. Deflandre gave the dimensions of the holotype as length 38y, breadth 32u. 
The observed specimens are larger than the holotype. 


RemaRKs: L. amabilis has been previously recorded only from the Kimmeridgian 
of France. It was infrequent in the samples from England and France, five speci- 
mens from the Lower Kimmeridgian (Baylei to Mutabilis Zones) and three specimens 
from the Upper Kimmeridgian (Pectinatus) being observed. It is recorded from 
English assemblages for the first time: the mode of archaeopyle formation for this 
species is also recorded for the first time. In general structure and tabulation, the 
observed specimens correspond closely to the holotype. 


Fic. 18. Leptodiniwm amabilis (Deflandre). Tabulation and archaeopyle formation 
(plate 3” is missing): left, in ventral view; right, in dorsal view. Specimen BM(NH) 
slide V.56350 (I). X c.1690. 


218 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


Leptodinium cf. crassinervum (Deflandre) Sarjeant, 1969 
Plate 3, figure 8, plate 5, figures 4-6; text-figure 19 


DeEscrIPTION: The shell is broadly ovoidal to polygonal in shape. The cyst wall 
is thick (c. 2:54) and densely granular. The crests are membraneous in character 
and arise from slight thickenings of the periphragm; although they are low, they are 
quite obvious. They give rise to occasional short spines, up to c. 4—4-5u in height. 
Tabulation: 4’, Ia, 6”, 6c, 6’”, Ip, Ipv, 1’”’’ and 2s. Plate 1’ is elongate, extending 
down almost two-thirds of the epitract. Plates 2’, 3’ and 4’ are more or less equal 
in size. The precingular plates are relatively large, except plate 6’’ which is reduced 
because of the large anterior intercalary plate (1a). The six postcingular plates are 
of variable shape and size: plate 2’ is reduced to accommodate the intercalary 
plate (1p) which is rather large. Plate 1’’’ is quite small; the other postcingular 
plates are relatively large, plate 4’’’ being the largest of all the plates. A crescent- 
shaped posterior ventral plate, Ipv, separates the sulcal plates from the single 
antapical plate. 

The cingulum is moderately narrow, formed by six plates (plate 6c is very small) ; 
it is slightly spiral, laevorotatory and divides the theca unequally: the epitract is 
twice as large as the hypotract. The sulcus is short and broad; its posterior portion 
is formed by two sulcal plates, one small, the second quite large. 


Fic. 19. Leptodinium cf. crassinervum (Deflandre). Tabulation and archaeopyle forma- 
tion: left, in ventral view; right, in dorsal view. Specimen BM(NH) slide V.56346 (1). 
x c.960. 


FROM ENGLAND, SCOTLAND AND FRANCE 219 


On the dorsal side of the shell, a large precingular archaeopyle is formed by loss of 
plate 3”. 

FIGURED SPECIMENS: BM(NH) slide V.56346(1), (3) and V.56351(1), Sample 
LO 353 from the Littleworth Quarry, Oxfordshire. Upper Kimmeridgian (Pallasioides 
Zone). 


DIMENsIons: Range of the observed specimens: overall length 68—80u, breadth 
50-68. Measured specimens 4 in number. 

Deflandre gave the following dimensions for L. crassinervum: length 82u, breadth 
69u. The English Kimmeridgian specimens found which are similar to Deflandre’s 
specimen, are slightly smaller. 


REMARKS: L. crassinervum has been recorded only from the Kimmeridgian of 
France (by Deflandre) ; the species was based on a single specimen and, because of its 
poor preservation, Deflandre was unable to determine the tabulation. Later Sarjeant 
re-studied the holotype and, on the basis of its similarity to other Jurassic species, 
re-attributed it to Gonyaulacysta. Recently, it was transferred to Leptodinium, on 
the basis of its lack of an apical horn. 

Four specimens observed, all from the Pallasioides Zone of England (sample 
LO 353), exhibit a strong resemblance, in their long epitract and thick shell wall, to 
L. crassinervum, but could not be attributed to that species with confidence, in absence 
of knowledge of the tabulation of the holotype. 


Leptodinium sp. 
Plate 3, figure 9; text-figure 20 


DESCRIPTION: Cyst spherical to subspherical, an appearance of polygonality 
being imparted by the crests. Tabulation: 4’, Ia, 6”, 6c, 6’’, Ip, 1’; plate 
boundaries bearing relatively high, delicate, distally denticulate crests. 

The first apical plate, 1’, is long and narrow, occupying the anterior extension of 
the sulcus. Plates 2’ and 3’ are comparable in shape and size, but plate 4’ is 
markedly larger. Between the plates 1’ and 4’, a small, elongate intercalary plate 
(Ia) is accommodated. The precingular plates are generally large, except plate 6”, 
which is narrow. The postcingular plates are also all quite large. Plate 6’” is 
slightly reduced. Because of the bad orientation of the specimen, the exact shape 
and size of plates 1’” and 2’” is not very clear, but plates 3’” and 4’” appear the 
largest of all the plates. The single large antapical plate (1’’’’) is pronouncedly 
convex. 

The cingulum is strongly helicoid, laevorotatory, occupied by six relatively large 


cingular plates. It divides the cyst unequally: the sulcus is sigmoidal in shape and 
_ extends between the apex and antapex, narrowing to the two ends. 


The surface is smooth and the wall is transparent. A precingular archaeopyle 


_ formed by loss of plate 3’’ was observed in some of the specimens. 


FIGURED SPECIMEN: BM(NH) slide V.56352, sample HC 246, from 140 ft below 
_the Massive Bed, Hounstout Cliff, Dorset. Upper Kimmeridgian (Rotunda Zone). 


D 


Fic. 20. Leptodinium sp. Tabulation and archaeopyle formation (plate 3” is missing): 
left, in oblique ventral view; right, in oblique dorsal view. BM(NH) slide V.56352. 
X c.1620. 


DIMENSIONS: Figured specimen: overall length 4ou, breadth 4ou. 
RANGE: Length 40-60u, breadth 30-52u. Measured specimens 11 in number. 
OBSERVED RANGE: Kimmeridgian (Wheatleyensis to Rotunda). 


REMARKS: Twelve specimens were observed in the Middle-Upper Kimmeridgian 
assemblages of England, which are comparable in their morphological features to 
Leptodinium, but differ from the other species of this genus. They possibly represent 
a new species. Unfortunately, all the specimens observed are somewhat crushed, 
folded and in a bad orientation; the figured specimen was the best. The small size 
and the transparent shell wall of the specimens increase the difficulty of determining 
the tabulation. Accordingly, no new specific name for these forms can yet be 
proposed. 

The most closely comparable species is L. amabilis, which is similarly small. 
However, these Kimmeridgian forms are clearly distinguished by the character of 
their crests, the presence of an anterior intercalary plate, the absence of the posterior 
ventral plate and the details of the rest of the tabulation. 


Genus OCCISUCYSTA Gitmez, 1969 


Occisucysta evitti (Dodekova) Gitmez, 1970 


1969 Gonyaulacysta evitti Dodekova, 14-15, pl. 1, figs 1-8, table r. 
1970 Occisucysta evitti (Dodekova) ; Gitmez, 269. 

DESCRIPTION: Cyst spherical, with the tabulation 4’, ?1a, 6’, 6-7c, 7’, Ip, Ipv, 
1’’’’, No true apical horn appears to be present, the apical prominence being 


FROM ENGLAND, SCOTLAND AND FRANCE 221 


formed by the confluence of crests. The cingulum is strongly helicoid, laevorotatory, 
dividing the cyst unequally: the epitract is slightly longer than the hypotract. The 
sulcus is short. The sutures bear delicate, perforate, membraneous crests, with 
denticulate edges. Around the apex, the crests are apparently higher than else- 
where. The surface is granular and tuberculate, also possessing lines of small spines 
which form “‘double sutures”, parallel to the true sutures. A precingular archae- 
opyle is formed by loss of plates 2’’ and 3”. 


Ho.otyPe: Dodekova’s collection, Jmp/DO-16. Tithonian, Bulgaria. 


Dimensions: Holotype: overall length 82u, breadth 82u, crests 4u, high on the 
sutures, apical crests 8y high. 


RemARKS: The description and dimensions mentioned here are as given by 
Dodekova. This species is characterized by a two-plate precingular archaeopyle. 
Although Dodekova did not mention the anterior intercalary plate (1a), the photo- 
graphs of the holotype of G. evztti show that the plate above 6” (which was indicated 
as plate 4’) is, in fact, plate 1a, a boundary being present at its anterior end, 
separating off a small plate 4’. The position of the plates 7’” and 1pv is exactly the 
same asin O. balios. In tabulation and the character of archaeopyle, therefore, this 
species corresponds to the genus Occisucysta and is accordingly reallocated to it, 
despite the lack of a true apical horn. Erection of a second genus, to accommodate 
hornless forms, may prove desirable in the future. 


Occisucysta monoheuriskos sp. nov. 
Plate 7, figures 10-11, text-figure 21 


DERIVATION OF THE NAME: Greek, monos, one, single, heurisko, find, discover; 
referring to the discovery of a single specimen. 


Diacnosis: A species of Occisucysta with a globular cyst. Tabulation: 4’, 6”, 
7c, 7'", Ip, Ipv, 1’, 2s. The epitract and hypotract are almost equal in size, 
separated by the only slightly spiral, laevorotatory cingulum. The sulcus is broad 
and short, stretching from about mid-point on the epitract to about mid-point on 
the hypotract. The surface is finely granular and sparsely tuberculate. Sutures 
are in the form of spine rows; the spines are distally closed, oblate or bifid, generally 
simple, but the spines near to the apical horn are connected distally and thus appear 
more complicated. Short spines surround the distal end of the apical horn like a 
corona. A two-plate precingular archaeopyle is typically present, forming by loss 
of plates 2’’ and 3”’. 

HoLotyre: BM(NH) slide V.56353(z). Sample CS 421, from the Sand Stone 
dyke, first lower Meleagrinella Band of Eathie Haven, South Cromarty, Scotland, 
Lower Kimmeridgian (Cymodoce Zone). 

Dimensions: Holotype: overall length 7ou, breadth 65y, horn length roy; length 
of the sutural spines 5y, length of the spines surrounding the apical horn 3y. 

Description: The cyst wall is relatively thick, c. 1:5u. The cylindrical horn 
rises from the top of the dome-shaped epitract and is formed by two of the four apical 


222 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


plates, 1’ and 2’. Plate 1’ is elongate and broad, corresponding in position to the 
anterior prolongation of the sulcus. The other three apical plates are relatively 
large and of more or less equal size. The six precingular plates, together with the 
apical plates, make up the epitract; no intercalary plates are present. Except for 
plate 6’, which is narrow and elongate, the precingular plates are quite large; plates 
2’ and 3” are lost in archaeopyle formation. The cingulum is occupied by 7 plates 
of variable size, the first and last (1c and 7c) being small. The ends of the cingulum 
are widely separated by a very broad sulcus, which widens further in its posterior 
portion. Two small plates are developed in the mid-portion of the sulcus. 

The hypotract is hemi-spherical. The first postcingular plate (1’’’) is small, 
quadrate and placed in the flank of the sulcus. Plate 2’” is roughly triangular, and, 
because of the presence of the intercalary plate (1p), is reduced in size. Plates 
3'", 4’ and 5’” are very large. Plate 6’” is narrow and elongate; plate 7’” is small. 
The single, convex antapical plate (1’’’’) is quite large. Two intercalary plates, Ip 
and Ipv, together form a crescent shape; Ipv separates the sulcus from the antapex. 


REMARKS: O. monoheuriskos has been found in only one sample (CS 421) and only 
one well preserved specimen has so far been observed. Its general shape, tabulation 
and the sutural features, combined with the two-plate precingular archaeopyle, 
agree with the diagnosis of the genus Occisucysta. Since all the morphologic features 
are discernible on the one well-preserved specimen, it is proposed without hesitation 
as a new species of Occisucysta. 

O. monoheuriskos is distinguished from the two other described species of the 
genus by its apical horn of different form and aspect, its lack of an anterior inter- 


Fic. 21. Occisucysta monoheuriskos sp. nov. Tabulation and archaeopyle formation 
(plates 2” and 3” are missing): left, in ventral view; right, in dorsal view. Holotype: 
BM(NH) slide V.56353 (1). xX c.1041. 


"maaan 


FROM ENGLAND, SCOTLAND AND FRANCE 223 


calary plate, and a number of details of the tabulation. In its possession of a 
cylindrical apical horn distally surrounded by spines and its spinous sutures, it shows 
some similarity to Occisucysta sp. of Gitmez (1969), but since bad preservation 
precluded any detailed knowledge of Occisucysta sp., an extended comparison is not 
possible. 


Cyst-Family MICRODINIACEAE Eisenack, 1964, emend. Sarjeant and Downie, 
1966 


Genus DICTYOPYXIS Cookson and Eisenack, 1960b 
Dictyopyxis areolata Cookson and Eisenack, 1960b 
Plate 7, figure 9 


1955 Membranilarvnax ovulum Valensi, 590, pl. 2, fig. 4, pl. 5, fig. 6. 

1960b Dictyopyxis aveolata Cookson and Eisenack, 255-6, pl. 39, figs 12-14. 

1961 Dictyopyxidia aveolata (Cookson and Eisenack); Eisenack, nomen nudum, 316. 

1962b Dictyopyxis aveolata Cookson and Eisenack; Sarjeant, 494, pl. 70, fig. 19; text-fig. 13, 
tables 2-3. 

1964 Dictyopyxidia aveolata (Cookson and Eisenack); Downie and Sarjeant, nomen nudum 110. 

1964 Dictyopyxis aveolata Cookson and Eisenack; Sarjeant, table 3. 

1966b Ellipsoidictyum areolata (Cookson and Eisenack); G. & M. Deflandre, fiches 3318-9. 

1967b Dictyopyxidia aveolata (Cookson and Eisenack); Sarjeant, nomen nudum table 2. 

1968 Dictyopyxis aveolata Cookson and Eisenack; Sarjeant, 229-30, pl. 1, fig. 1; text-fig. 5. 

1970 Dictyopyxis sp. Gitmez, 275-6, pl. 1, fig. 1, table 4. 


DEscriPTION: This form is characterized by its highly reticulate surface. Each 
small field is demarcated by high sutures. The cyst is ovoidal to subspherical in 
shape. The arrangement of reticulae as a pattern of tabulation suggested by 
Sarjeant (1968) was not determined; however, some small fields on the equatorial 
plane together form a median line, which may well be equivalent to the cingulum. 
The apex is lost in archaeopyle formation. 


FIGURED SPECIMEN: BM(NH) slide V.53956(1). Sample OM 420, from 2o ft 
above the Ringstead Coral Bed, west of Osmington Mills, Dorset. Lower 
Kimmeridgian (Baylei Zone). 

Dimensions: Figured specimen: overall length (apex lacking) 55u, breadth 5ou. 
Range of the English specimens (3 specimens were measured): overall length 50-55n, 
length without apex 30u, breadth 40-50u. Scottish specimens: length (apex lacking) 
45-60u, breadth 40-554 (3 specimens measured). French specimens: overall 
length 50-60y, length without apex 35-50p, breadth 35-52. (6 specimens measured). 

Cookson and Eisenack gave the range for the Australian specimens as 86-124 
length and 54—66u breadth, which makes them larger than the European Kimmer- 
idgian specimens. 

OBSERVED RANGE: Lower Kimmeridgian (Baylei to Mutabilis). 


TOTAL KNOWN RANGE: Upper Callovian (Lamberti) to Lower Kimmeridgian 
(Mutabilis). 


224 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


REMARKS: D. areolata was described originally from the Oxfordian to Lower 
Kimmeridgian of Australia; subsequently, Sarjeant recorded it from the Oxfordian 
of England (1962) and the Callovian of France (1968). The specimens illustrated 
by Valensi as Membranilarnax ovulum, from Magdalenian flints of presumed Upper 
Jurassic age, appear attributable to this species. 

Three specimens from Scotland, eight specimens from France and four specimens 
from England were observed; they occur only in the Lower Kimmeridgian assem- 
blages. These specimens agree in their morphologic features with the holotype of 
D. areolata. 


Dictyopyxis cf. reticulata (Valensi) Sarjeant, 1968 
Plate 7, figures 4-5; Plate 12, figures 1-2 


DESCRIPTION: The shell is ovoidal with a reticulate surface; the reticulation is 
irregular. The crests surrounding the small areas are not so high as in D. areolata. 
Spines rise up from the crest nodes; they are solid, simple, oblate or bifid. There is 
no obvious tabulation, but more regularly formed reticulae make up a median band 
equivalent to a cingulum. A large apical archaeopyle, with polygonal outline, is 
developed. 

FIGURED SPECIMENS: BM(NH) slide V.56354(1). Sample OF 485, from the road 
side, Montard d’Oignon, France. Lower Kimmeridgian (Mutabilis Zone). 

BM(NH) slide V.56355(z). Sample 486, from the top of the Oignon Beds, west of 
Lac du Chavoley, France. Lower Kimmeridgian (Mutabilis Zone). 

DIMENSIONS: Range of the French specimens (7 specimens measured) overall 
length 50-61y, length without apex 30-55u, breadth 23-65y, spine length 6-8y. 
Scottish specimen: length (apex lacking) 35yu, breadth 48y. Valensi gave the 
dimensions for this species as 45y length (apex lacking) and 52y breadth, spine 
length, 3. The Kimmeridgian specimens are similar in size, but their spines are 
longer than those of the holotype. 

Remarks: D. reticulata was recorded from the Bajocian of Calvados and 
Bathonian of Vienne, as a species of Palaeoperidinium, by Valensi. It was trans- 
ferred to the genus Dictyopyxis by Sarjeant (1968). Single specimens from the 
Cymodoce Zone of Scotland and France and eight specimens from the Mutabilis 
Zone of France were recorded, which are closely similar to the specimen figured by 
Valensi, except for a greater length of the spines arising from the crest nodes. In 
view of this minor difference in morphology and the stratigraphical hiatus, these nine 
specimens were compared with, but not placed in, D. reticulata. 


Genus MEIOUROGONYAULAX Sarjeant, 1966a 
Meiourogonyaulax staffinensis Gitmez, 1970 
Plate 9, fig. 4 
1970 Meiourogonyaulax staffinensis Gitmez, 276-8, pl. 3, fig. 1, text-fig 20 a, b. 
FIGURED SPECIMEN: BM(NH) slide V.56356, specimen ED 242, Kimmeridge Clay 


FROM ENGLAND, SCOTLAND AND FRANCE 225 


(Pectinatus Zone) 60 ft above Freshwater Steps Stone Band, Egmont Bight, Dorset. 


DIMENSIONS: Overall length (apex lacking) 84, overall breadth g1-5y, length of 
cyst alone 72u, breadth 81-5u, height of crests 5-gu. 

RANGE OF DIMENSIONS: Overall length (apex lacking) 45-98u, overall breadth 
42-915. 

OBSERVED RANGE: Kimmeridgian (Baylei to Pallasioides). 

REMARKS: This species, hitherto recorded only from the Baylei Zone, ranges 
throughout the Kimmeridgian (though it has not been encountered in some zones). 
The size range here quoted is significantly greater than that originally quoted 
(overall length 48—80y, overall breadth 45-78): the specimen figured is one of the 
largest encountered. 


Meiourogonyaulax dicryptos sp. nov. 
Plate 7, figure 6; text-figure 22 


DERIVATION OF THE NAME: Greek, di-, two, double; kvypto, cover; referring to the 
two-layered shell wall. 


DiaGnosis: Cyst subspherical to spherical, with the tabulation 4’, 6”, 6c, 7’”, 
Ip, 1’, poorly marked by low ridges. Cingulum more or less equatorial and 
circular. Sulcus deep, short, confined to the hypotract, broadening towards the 
antapex. Cyst wall thick and composed of two layers: thick endophragm and thin 
periphragm. The periphragm bulges out on the apex to form a blunt apical horn, 
a cavity being developed between the two layers. Surface of the cyst is densely 
granular. Apical archaeopyle always present: sometimes the operculum remains 
attached to the shell, ventrally. 


Fic. 22. Meiourogonyaulax dicryptos sp. nov. Tabulation and archaeopyle formation: 
left, in ventral view; right, in dorsal view. Holotype, specimen BM(NH) slide V.56357 
(1). xX €,1063. 


226 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


HoLotyPE: BM(NH) slide V.56357(1). Sample BN 179, from the Marnes a 
Harpagodes, Benerville, Normandy. Lower Kimmeridgian (Cymodoce Zone). 


Dimensions: Holotype: length (apex lacking) 4ou, breadth 52. 


RANGE: overall length 70-gou, breadth 52-88y, length (apex lacking) 40-64y. 
Measured specimens 8 in number. 

DESCRIPTION: The spherical to subspherical cyst is divided into two equal parts 
by the moderately narrow cingulum. Both epitract and hypotract are dome-shaped; 
the epitract bears a small, blunt, hollow apical horn. Four apical and six precingular 
plates make up the epitract: plate 1’ is elongate, the other apical plates are broader. 
Plates 1’ and 6” are somewhat reduced and plates 2” and 5” are the largest of the 
precingular plates. Seven postcingular plates are present on the hypotract. Plates 
1’” and 2’” are reduced because of the presence of a large intercalary plate (rp). 
Plates 3’, 4”, 5’” and 6’” are relatively large; plate 7’” is reduced. The single 
antapical plate (1’’’’) is quite large and convex. The cingulum is poorly indicated, 
formed by six plates of variable size. The sulcus is deep and, in its posterior portion, 
very wide. An apical archaeopyle forms by loss of the apical plates. 

OBSERVED RANGE: Kimmeridgian (Cymodoce, Pectinatus and Rotunda Zones). 

REMARKS: Eight specimens (one from France, seven from England) were recorded. 
These specimens differ from the other species of the genus in the character of their 
tabulation and possession of a hollow apical horn. In the presence of a seventh 
postcingular plate, this new species differs from the typical Meourogonyaulax 
tabulation: however, it corresponds in all other respects. 


Meiourogonyaulax pila sp. nov. 
Plate 4, figure 5, plate 7, figure 3; text-figure 23 


DERIVATION OF THE NAME: Latin, pila, ball; referring to the shape of the cyst. 

Diacnosis: Cyst almost circular in outline, without an apical horn and rounded 
at the antapex. Wall moderately thin, surface finely granular. Tabulation: 4’, 
6’’, 6c, 6’’’, Ip, Ipv and 1’’’".. Plate boundaries faintly indicated. The cingulum 
forms a feebly laevorotatory spiral. Apical archaeopyle typically present, with 
operculum attached ventrally. 

HorotyrPe: BM(NH) Slide V.56358; sample FD 236, from + mile west of Fresh- 
water Steps, Dorset. Middle Kimmeridgian (on the boundary of the Pectinatus and 
Hudlestoni Zones). 

PARATYPE: I.G.S. Slide PK.121, sample WB 19, from H.M. Geological Survey 
Borehole, Warlingham, Surrey, at 2535 ft 3in. depth. Middle Kimmeridgian 
(Wheatleyensis Zone). 

DIMENSIONS: Holotype: overall length 60, breadth 55u. Range of the observed 
specimens (Ig in number): length 55—75u, breadth 55—7ouw. 

DESCRIPTION: The spherical cyst 1s divided by the moderately wide and more 
or less equatorial cingulum into two parts, the epitract and the hypotract ; these may 


} 
| 
' 


| 


FROM ENGLAND, SCOTLAND AND FRANCE 227 


Fic. 23. Meiourogonyaulax pila sp. nov. The holotype, with attached operculum. 
Left, in ventral view; right, in dorsal view. BM(NH) slide V.56358. x c.1018. 


be equal in size or the hypotract may be slightly longer than the epitract. The 
sulcus is relatively short, mainly placed on the hypotract. 

Plate 1’ is elongate, the other three apical plates are more or less similar in shape 
and size. The precingular plates are generally almost equal in size, except that 
plate 6” is smaller than the others. The postcingular plates are of variable size: 
plate 1’” is relatively small, plate 4’” is the largest of all the plates. A quite large 
intercalary plate (Ip) is situated between the plates 2’” and 1’’”’; plate 2’” is corres- 
pondingly reduced. A large posterior ventral plate (Ipv) separates the sulcus from 
the antapex. A single antapical plate, broad and slightly convex, occupies the 
antapex. Plate boundaries are marked by low ridges. 


RemaRKs: In general appearance, M. pila is similar to the members of the genus 
Canningia, for example C. minor and C. ringnesit; however, since the species of 
Canningia exhibit no tabulation, except for the weakly indicated cingulum, there is 
no possibility of confusion with M. pila. Because of the tabulation and apical 
archeopyle, the species is clearly attributable to Metourogonyaulax. M. pila was 
recorded from the Middle and Upper Kimmeridgian (Scitulus to Rotunda Zones) 
from England only: it was not observed in Lower Kimmeridgian assemblages. 


Meiourogonyaulax sp. 


Plate 4, figure 4, plate 7, figure 12 


DESCRIPTION: Cyst broadly ovoidal, almost spherical in shape, without apical 
horn and with rounded antapex. There is often no indication of tabulation, but in 


28 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


2 


some of the specimens two apical and three precingular plates were recognised with 
difficulty on the dorsal side. The cingulum is frequently weakly indicated. The 
cyst wall is thick and is densely granular. An apical archaeopyle is typically present, 
formed by the rupture of the apex along a more or less straight line with small V- 
shaped notches along the edge, corresponding to the positions of sutures. Generally, 
the operculum remains attached ventrally. 


FIGURED SPECIMENS: BM(NH) slide V.56359(1). Sample LO 352 from the 
Littleworth quarry, Oxfordshire. Upper Kimmeridgian (Pallasioides Zone). 1.G.S. 
slide PK.100, sample WB 1, from H.M. Geological Survey Borehole, Warlingham, 
Surrey, at 7984 ft 7 in. depth. Lower Kimmeridgian (Mutabilis Zone). 


DIMENSIONS: Figured specimen from Warlingham Borehole: overall length 75y, 
breadth 68. Figured specimen from Littleworth: overall length 63y, breadth 6o0u. 
Range: overall length 48-95y, breadth 46-85. Measured specimens 15 in number. 


ReMARKS: A group of specimens (22 in number) observed in the Kimmeridgian 
of England are, in their general appearance, with granular surface and attached 
operculum, similar to Canningia ringnesi (recorded from the Upper Cretaceous of 
the Arctic by Manum and Cookson, 1964). However, they differ in that they have 
a relatively thick cyst wall and tabulation (albeit poorly indicated). Because of 
the mode of archaeopyle formation and the slight indication of a tabulation, these 
specimens are allocated to the genus Meiourogonyaulax. It is possible that they 
may be intermediate forms between the two genera, in which the tabulation is 
becoming progressively less apparent. 


Genus EGMONTODINIUM gen. nov. 


DERIVATION OF NAME: Named after the type locality—Egmont Bight, Dorset. 


DiaAGnosiIs: Proximate cyst, spherical to ovoidal. Tabulation typically 4’, 5 or 6 
ac., 6’, 6c, 6’, op, 2pv, Ope, 1’’”’: additional, very small platelets may be developed 
at crest nodes and the posterior tabulation is subject to some variation. No apical 
or other horns are developed. Crests or spinelets may arise from the sutures and 
spines may also be present, singly or in rows, on some plates. Archaeopyle apical, 
formed by schism along the anterior circle; the operculum frequently remains 
attached. 


TyPE SPECIES: Egmontodinium polyplacophorum sp. nov. Kimmeridge Clay 
(Kimmeridgian: Pectinatus Zone), Egmont Bight, Dorset. 


REMARKS: This genus is distinguished from all others yet described inits tabulation. 
The plates surrounding the apex might be termed anterior intercalaries: the authors, 
however, feel that this would be inappropriate, since they are not merely interposed 
between existing reflected plate series but constitute an additional series. The new 
name “‘anterior circle plate” is thus coined for them. The plates surrounding the 
antapex are similarly designated “‘posterior circle plates”, following the precedent 
of another Jurassic genus, Pluriarvalium. 

The most comparable genus is Ellipsoidictywm Klement 1960, whose complex 
tabulation was described in detail by Gocht (1970, pp. 150-2): however, the tabula- 


FROM ENGLAND, SCOTLAND AND FRANCE 229 


tion of the epitract of this genus is markedly dissimilar and a close affinity cannot be 
considered probable. 

The familial allocation of this genus is based on its proximate character and apical 
archaeopyle: the tabulation does not accord with that specified by its authors for 
this cyst family and a reallocation may prove necessary in the futute. 


Egmontodinium polyplacophorum sp. nov. 
Plate 8, figures 1-4; Plate 9, figure 3; Plate 11, figures 5-6, 8; text-figure 24 


DERIVATION OF NAME: In reference to the large number of plates developed. 


Diacnosis: A species of Egmontodinium having an ovoidal cyst, thin walled and 
without prominent granulation or punctation. Sutures variably ornamented with 
delicate crests or with rows of spinelets, simple or bifurcate and sometimes distally 
connected; the sutural ornamentation is most prominent around the antapex. The 
tabulation is as for the genus, but shows some variation in detail through the 
presence or absence of additional small plates at sutural nodes. 


Ho.LotyPe: BM(NH) slide V.56360(2b), Kimmeridge Clay (Pectinatus Zone) 
60 ft above Freshwater Steps Stone Band, Egmont Bight, Dorset. Paratypes: a. 
BM(NH) slide V.56360(1)._  b. BM(NH) slide V.56360(2a), showing apical archaeopyle. 
c. BM(NH) slide V.56347(1), also showing archaeopyle. [All paratypes are from the 
same locality and horizon as the holotype. | 


DimEnSIONS: Holotype: length of cyst 76u, breadth 58, maximum height of 
crests 3°5u. Paratype a: length 78, breadth 61-5u, maximum height of crests 3u. 
Paratype b: length (apex lacking) 68, breadth 59:5u, maximum height of crests 
c. 5u. Paratype c: length (apex lacking) 6Iu, breadth 661, maximum height of 
crests c. 5:5u. Range: overall length 60-80y, length without apex 50-68y, breadth 
45-65u., maximum height of crests c. 3-5u. Measured specimens: 15. 


DescriPTIOn: The cyst surface is typically smooth, but may exhibit minute 
granulation or punctation. Ornament is normally confined to the sutures: in some 
instances, however, one or a few isolated spines, or a short row of spines not traversing 
the plate, may be present within a plate boundary. 

Four apical plates are developed, the first being the largest and situated in the 
anterior prolongation of the sulcus. They are surrounded by six (possibly sometimes 
by only five) elongate plates constituting the anterior circle, plate 3ac being broader 
than the others in the holotype. The opercular suture opens along this circle, so 
that the plate boundaries with the apical plates are present in the operculum and 
those with the precingular plates on the cyst proper. The initial opening of the 
opercular suture appears to occur on the dorsal side: the operculum frequently 
retains a ventral attachment with the abandoned cyst. The holotype shows no 
opening: paratype (a) is partly open, though the operculum remains attached and 
almost in place; paratypes (b) and (c) lack the operculum. 

The six precingular plates are almost of equal size. In the holotype, a small 
round plate is present at the node of the crest separating plates 3’ and 4” and that 
bounding the operculum: no such plate was distinguished on the paratypes. The 


230 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


4’ 


6a 
(paca Sac 
6" 2 


Fic. 24. Egmontodinium polyplacophorum gen. et. sp. nov. Reconstruction of the tabula- 
tion, A~-B Holotype, BM(NH) slide V.56360 (2b) in ventral view and dorsal view. C-D 
Paratype (a), BM(NH) slide V.56360 (1) in ventral and dorsal view. x c.958. 


FROM ENGLAND, SCOTLAND AND FRANCE 231 


cingulum is made up of six elongate plates with clear boundaries. The sulcus is 
broad and occupies only the central part of the ventral surface, being separated 
from the apex by the large plate 1’ and from the antapex by two posterior ventral 
plates and by two plates of the posterior circle. In the holotype, a small plate is 
present at the junction of the sulcus and plate 6’”. 

Of the six postcingular plates, the first is extremely small (as is the case in many 
species of Gonyaulacysta) and may be masked by its bounding crests: plate 2’’’ is also 
reduced, to accommodate the second posterior ventral plate, an equivalent of the 
posterior intercalary plate but displaced to the ventral side. The other four post- 
cingular plates are quite large. The plates of the posterior circle are quite variable 
in form: in particular, plates 3pc and 5pc sometimes exhibit a remarkable “‘tail’’ 
extending along the sulcus separating two dorsal postcingular plates. The boundaries 
between the ventral posterior circle plates are in some instances distinguishable only 
with difficulty, if at all: the holotype is unusually clear in structure and exceptionally 
favourably orientated. The antapical plate is polygonal and quite large: on two 
specimens (paratypes a and c) it is partially subdivided by a row of proximally 
connected spines, but this row only traverses half the plate. 

The ornamention of the sutures is highly variable, from rows of isolated, simple or 
bifurcate spines, with or without distal or (more commonly) proximal connections, 
to simple delicate crests of moderate height. The highest crests are generally those 
bounding the cingulum and antapex. (The character of the crests may be modified 
by accidents of preservation.) The crests or spines are usually little more than one- 
tenth of the cyst breadth in height: difficulty is often experienced in distinguishing 
particular crests. 


OBSERVED RANGE: Middle to Upper Kimmeridgian (Wheatleyensis to Pectinatus 
Zones). 


Cyst-Family PAREODINIACEAE Gocht, emend. Sarjeant & Downie 1966 
Genus APTEODINIUM Eisenack, 1958 
Apteodinium cf. maculatum Eisenack & Cookson 
Plate 12, figure 6 


FIGURED SPECIMEN: I.G.S. slide PK.105, sample WB 4, from H.M. Geological 
Survey Borehole, Warlingham, at 2g10 ft 6in. depth. Lower Kimmeridgian (Eudoxus 
Zone). 


DIMENSIONS: Figured specimen: overall length 83, breadth 80u. 


RANGE: (7 specimens measured): length 50-83u, breadth 45-80y, apical horn 
length 3-4. Range of the dimensions of Australian specimens, as given by 
Eisenack and Cookson: length 74-105, breadth 70-105y. The Kimmeridgian 
specimens are thus of comparable size. 


REMARKS: Nine specimens recorded, seven from English and two from French 
assemblages, are similar to A. maculatum, as recorded and described from the 
Albian by Eisenack and Cookson. They differ from the Australian specimens in 


232 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


having a precingular archaeopyle and in the absence of the small thickened areas 
with circular outlines that give A. maculatwm its characteristic appearance; in only 
one specimen, from the Warlingham assemblage, were similar small circular areas 
observed. The Kimmeridgian specimens must be thus considered only comparable 
to, and not definitely conspecific with, the Australian specimens. 


OBSERVED RANGE: Lower to Middle Kimmeridgian (Baylei to Rotunda Zones). 
Not yet observed from the Cymodoce and Elegans Zones. 


Genus IMBATODINIUM Vozzhennikova, 1967b 
Imbatodinium antennatum sp. nov. 
Plate 11, figures 2-3 
1970 Imbatodinium sp. Gitmez, 282, pl. 7, fig. 5, table 4. 


DERIVATION OF THE NAME: Latin, antenna, feeler, a sensory appendage on the head 
of an insect—with reference to the similarity of the process rising up from the apical 
horn of this species to an insect’s antenna. 


Diacnosis: A proximate cyst, elongate to ovoidal in shape, with a strong apical 
horn. On the distal end of the horn, there is a thread-like projection of variable 
length ending in a small knob. In some cases, a cingulum is weakly developed; but 
there is no indication of tabulation or sulcus. The surface of the cyst is granular. 
An intercalary archaeopyle is often developed. 


Ho.otyPe: I.G.S. slide PK.124, sample WB 23, from H.M. Geological Survey 
Borehole, Warlingham, Surrey, at 2434 {t 6in. depth. Middle Kimmeridgian (Hudle- 
stoni Zone). 


PARATYPE: BM(NH) slide V.56361(1), sample ED 242, from 60 ft above the Fresh- 
water Steps Stone Band, Egmont Bight, Dorset. Upper Kimmeridgian (Rotunda 
Zone). 


Dimensions: Holotype: overall length 73u, breadth 35y, apical horn length 
without projection gu, with projection I6u. Range of the observed specimens 
(16 in number): overall length 62-100p, breadth 28—5ou, overall length of horn 12— 
30p, horn length without projection 7-16y, length of the projection 4-14u. 

DESCRIPTION: The cyst is elongate, broadening in the posterior median 
region. The apical horn is well developed, bearing a thread-like process of 
variable length, generally between half and one-third of the overall horn length. 
This thread-like process ends in a small bulge, which appears as a knob. The 
cingulum is only weakly developed, but may be suggested by faint surface marking. 
The epitract is longer than the hypotract, comprising almost two-thirds of the overall 
length. 


OBSERVED RANGE: Lower to Upper Kimmerdigian (Baylei to Rotunda Zones). 
Not yet observed from the Cymodoce and Elegans Zones. 

REMARKS: This new species of Imbatodinium is distinguished from the previously 
described species in its general shape, presence of an intercalary archaeopyle and 


FROM ENGLAND, SCOTLAND AND FRANCE 233 


characteristic shape of the apical horn. In horn shape, it is similar to J. villoswm, 
which was recorded from the Upper Jurassic of Russia by Vozzhennikova, but it 
differs from J. villosum in the absence of the sutural spines distributed all over the 
surface. 

I. antennatum is present in the Kimmeridgian assemblages of England, Scotland 
and France; however, it is infrequent ; one specimen from France, one specimen from 
Scotland and fifteen specimens from England being recorded. It is rare in the 
Lower Kimmeridgian, in which only four specimens were observed. The number 
increases in the upper horizons: five specimens were recorded from the Middle 
Kimmeridgian and seven specimens from the Upper Kimmeridgian. 


Imbatodinium cf. villosum Vozzhennikova, 1967b 
Plate 11, figure 1 


Description: The cyst is broadly ovoidal, elongate, with a broad based apical 
horn, distally bearing a process. There is neither tabulation nor sulcus; the cingulum 
is only faintly indicated. The epitract is longer than the hypotract, comprising 
almost three-quarters of the whole length of the cyst. The surface of the cyst is 
coarsely granular and covered by short, thick spines. An archaeopyle, intercalary 
in position, is occasionally present. 


FIGURED SPECIMEN: BM(NH) slide V.56362(1), sample HC 243, from c. 100 ft 
below the Rotunda Nodules Bed, Chapmans Pool, Dorset. Upper Kimmeridgian 
(Pectinatus Zone). 


DIMENSIONS: Figured specimen: overall length 80u, breadth 4op, horn length 
17u. Range: overall length 70-87y, breadth 40-52y, overall length of horn 8-17, 
horn length without process 4-13, apical process length 4-6; length of the spines 
over the surface 2:5-4u. Dimensions of J. villosum as given by Vozzhennikova: 
overall length 70:5—100p, breadth 27—40°5y, apical horn length 10-5-13°5y. 

REMARKS: Seven specimens observed in the Upper Kimmeridgian (Pectinatus 
to Pallasioides Zones) assemblages of England are similar to J. villosum, but smaller 
and the spines distributed on the surface are relatively shorter; for these reasons, 
they are compared with, rather than attributed to J. villosum. Vozzhennikova 
recorded this species from the Upper Jurassic of the Moscow Province, U.S.S.R. 


Cyst-family UNCERTAIN 
Proximate cyst sp. indet. 
Plate 11, figures 4, 7, 9 


DeEscripTION: The shell is broadly ovoidal to subspherical, with two blunt apical 
horns: the apex is rounded. Tabulation is very faintly indicated; four apical 
plates, six precingular and one antapical plate were determined with difficulty. The 
cingulum is indicated by inbulges on the sides of the cyst; the sulcus was not 
observed. The epitract is longer than the hypotract, so far as is determinable from 


234 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


the feeble indications of the cingulum. The archaeopyle is well developed, but in a 
very different way from the observed archaeopyle types in recorded species: the 
apex as a whole, together with one of the precingular plates, is thrown off in the 
archaeopyle formation, though the apex remains attached to the cyst. The surface 
of the cyst is densely granular; irregularly formed lumps (verrucae) were present on 
three of the observed specimens. 


FIGURED SPECIMENS: BM(NH) slide V.56363(1) and V.56364, sample FD 236, 
from +} mile west of Freshwater Steps, Dorset. Middle Kimmeridgian (from the 
boundary of the Pectinatus and Hudlestoni Zones). 


DIMENSIONS: Range of the observed specimens (4 in number): overall length 
66-83, breadth 60-75u. 

REMARKS: Four specimens were observed, in the English Middle and Upper 
Kimmeridgian assemblages (Wheatleyensis to Rotunda Zones). In its mode of 
archaeopyle formation, this form is different from all previously described proximate 
cysts. Because of the bad preservation and dense surface ornamentation, full 
details of the morphology could not be obtained; in consequence, no new taxon is 
proposed. 


Cyst-Family ADNATOSPHAERIDIACEAE Sarjeant and Downie, 1966 
Genus ADNATOSPHAERIDIUM Williams & Downie, 1966 
Adnatosphaeridium paucispinum Klement, 1960b, comb. nov. 
Plate 10, figures 1-4 


1960 Cannosphaeropsis paucispina Klement, 72, pl. 10, figs 9-10. 
1964 C. paucispina Klement; Downie & Sarjeant, 1or. 
1964 C. paucispina Klement; Sarjeant, table 3. 


DESCRIPTION: Cyst subspherical to ovoidal in shape, with a thin, smooth shell 
wall bearing slender, hollow processes, open distally and branched or broad, funnel- 
shaped, fenestrate. The processes are connected distally by trabeculae. An apical 
archaeopyle with a zig-zag margin was seen in almost all observed specimens. 

FIGURED SPECIMENS: BM(NH) slide V.56365(1) and V.56366(2), sample BN 179, 
from the Cymodoce Zone of Benerville, Normandy. 

DIMENSIONS: Range (8 specimens were measured): length 40-55, breadth 35-60n, 
length without apex (6 of the measured specimens have apical archaeopyles) 30—50p, 
process length 15-30u. 

OBSERVED RANGE: Lower to Middle Kimmeridgian (Cymodoce to Hudlestoni/ 
Pectinatus boundary). 

TOTAL KNOWN RANGE: Upper Oxfordian (Malm Alph.) to Middle Kimmeridgian 
(Hudlestoni/Pectinatus Boundary). 

REMARKS: This species has previously been recorded from the Upper Oxfordian 
of Germany by Klement (1960). It is now placed in the genus Adnatosphaeridium 
on the basis of the presence of an apical archaeopyle. The observed specimens 


FROM ENGLAND, SCOTLAND AND FRANCE 235 


were recorded from the Lower Kimmeridgian (Cymodoce Zone) of Normandy and 
Middle Kimmeridgian (Boundary of Hudlestoni and Pectinatus Zones) of Dorset. 


Cyst-Family HYSTRICHOSPHAERIDIACEAE Evitt, emend. Sarjeant and 
Downie, 1966 


Genus CLEISTOSPHAERIDIUM Davey, Downie, Sarjeant and Williams, 1969 
Cleistosphaeridium sp. 
Plate 15, figure 3 


DEscRIPTION: The cyst is spherical to subspherical, the wall thin and granular. 
Transparent processes, approximately 60 in number, are present: they are simple, 
conical, hollow and closed distally; their length is generally less than one-third of 
the cyst length. An apical archaeopyle is sometimes developed. 


FIGURED SPECIMEN: BM(NH) slide V.56367(1), sample ED 242, from 60 ft above 
the Freshwater Steps Stone Band, Dorset. Upper Kimmeridgian (Pectinatus Zone). 


DIMENSIonsS: Figured specimen: Cyst length (apex lacking) 50u, breadth 5oyn, 
process length 12u. Range (16 specimens measured): cyst length 38-60, length 
without apex 40-50u, breadth 38-66, length of the processes 10-22u. 


OBSERVED RANGE: Lower to Upper Kimmeridgian (Autissiodorensis to Rotunda 
Zones). Not yet observed from the Scitulus-Hudlestoni Zones. 


RemARKS: Although quite a number of specimens (31 in number) were recorded, 
the preservation was consistently very bad: they were always found covered by 
debris, so that there was no chance to examine them in detail sufficient to justify 
giving a specific name. They accord in general appearance, number and type of 
processes and apical archaeopyle, with the genus Cleistosbhaeridium. The most 
similar species is perhaps C. machaerophorum Deflandre and Cookson (1955), which 
was recorded from the Miocene of Australia, but the bad preservation precluded any 
detailed study. 


Genus OLIGOSPHAERIDIUM Davey and Williams, 1966 
Oligosphaeridium pulcherrimum (Deflandre and Cookson) Davey and Williams, 
1966 
Plate 13, figure 3, text-figure 25 


1954 Hystrichosphaeridium pulcherrimum Deflandre & Cookson, text-fig. 6, nomen nudum. 

1955 H. pulcherrimum Deflandre & Cookson, 270, pl. 1, fig. 8, text-fig. 21. 

1955 H. pulcherrimum Deflandre & Cookson; Valensi, 592, pl. 4, fig. 1. 

1957 4H. pulcherrimum Deflandre & Cookson; Delcourt & Sprumont, 59, pl. 1, fig. 4, pl. 2, 
figeei2. 

1964 H. pulcherrimum Deflandre & Cookson; Downie & Sarjeant, 121. 

1966 Oligosphaeridium pulcherrimum (Deflandre & Cookson); Davey & Williams, 75-6, pl. 10 
fig. 9, pl. 11, fig. 5; table r. 

1967b O. pulcherrimum (Deflandre & Cookson); Sarjeant, table 6. 


E 


236 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


1967 Hystrvichosphaeridium pulcherrimum Deflandre & Cookson; Clarke and Verdier, 54-5 
1. ro, figs 4-5. 
1970 Oh ae ie pulcherrimum (Deflandre & Cookson); Gitmez, 290 pl. 7, fig. 7, table 4. 
DESCRIPTION: The subspherical cyst possesses processes of two types. Some 
processes are tubular, distally open, widening distally and assuming a funnel shape 
with fenestrate walls (characteristic for this species) ; the other processes are simple, 
bifid or foliate. Because of the complication of the processes and bad preservation, 
accurate determination of the reflected tabulation was not possible, but the tabu- 
lation 6’, 5’, Ip, 2’’”’, 3s may be suggested, with five additional simple processes 
that could not be named and appear random in distribution. The surface of the 
shell is smooth. Apical archaeopyle developed. 


FIGURED SPECIMEN: BM(NH) slide V.56368(1), sample CC 449, from c. ro ft from 
the top of the Calcaires du Moulin Wibert, Cap de la Creche, Boulonnais. Lower 
Kimmeridgian (Baylei Zone). 

Dimensions: Figured specimen: length (apex lacking) 4ou, breadth 50u, process 
length 25-28u. Range (4 specimens observed): length (apex lacking) 35-48p, 
breadth 45-55y, process length 18-35y. Dimensions of the holotype: overall 
diameter c. 118u, process length 26-38u (as quoted by Deflandre and Cookson). 


REMARKS: This species first recorded from the Jurassic by Gitmez (1970). Un- 
fortunately, all specimens observed are in too poor condition for examination in 
detail. Four specimens were recorded, all from the Lower Kimmeridgian (Baylei 
Zone) assemblages, two of them from Dorset and two from France. 


Fic. 25. Olhgosphaeridium pulcherrimum (Deflandre & Cookson). Specimen showing the 
suggested tabulation: left, in ventral view; right, in dorsal view. BM(NH) slide V.56368 
(@a e648" 


FROM ENGLAND, SCOTLAND AND FRANCE 237 


Genus SYSTEMATOPHORA Klement, 1960b 
Systematophora ovata sp. nov. 
Plate 14, figures I-3 
1970 Systematophora sp. Gitmez, 296, pl. 8, fig. 5, table 4. 


DERIVATION OF THE NAME: Latin, ovatus, egg-shaped, with reference to the shape 
of the cyst. 


Diacnosis: A species of Systematophora having an elongate, ovoidal cyst bearing 
short processes (not more than one-fourth of the cyst breadth). The processes are 
located in groups: there are ten such groups, one occupying the apex, an opposite 
one the antapex, whilst eight groups are distributed between the apex and the 
antapex, four of them on the epitract, the other four on the hypotract. There is 
no connection between the groups of processes or between the processes in each 
group. The processes are simple, bifid distally or broad based, foliate and deeply 
forked at their distal end. The surface of the shell is finely granular. When an 
archaeopyle is developed, it is apical in position. 


Hototyre: BM(NH) slide V.53962(1), sample SC 444, from the Great Ouse River 
Board Pit, Stretham, Cambridgeshire. Lower Kimmeridgian (Baylei Zone). 


PARATYPE: BM(NH) slide V.56343(2), sample HC 243, from c. 100 ft below the 
Rotunda Nodules, Hounstout Cliff, Dorset. Upper Kimmeridgian (Pectinatus Zone). 


Dimensions: Holotype: shell length (apex lacking) 35u, breadth 28y, process 
length 6-8. Paratype: shell length 58y, breadth 4oy, process length 8y. Range: 
shell length 58—60u, apex lacking 35-48y, breadth 28—45u, process length 8-1Iy. 
Measured specimens were 6 in number. 


DESCRIPTION: The cyst wall is composed of two layers, the periphragm forming 
the processes. Both of the layers are thin and transparent. There is no connection 
between the processes at their proximal and distal ends; they arise separately from 
each other, positioned around the margins of ovoidal or polygonal fields whose shape 
is clearly shown by the broad bases of the processes. 

REMARKS: This new species was observed very infrequently in the Lower and 
Upper Kimmeridgian: one specimen was recorded from the Baylei Zone, three 
specimens from the Pectinatus Zone and one specimen from the Pallasioides Zone of 
England. Only one specimen was observed in the Scottish assemblages and none 
from France. The preservation of the specimens was moderately good. This new 
species differs from all previously described species of the genus on the basis of shape 
and character of its processes, in combination with the shape of the cyst. 


Cyst-Family UNCERTAIN 
Genus STEPHANELYTRON Sarjeant, I1961a 


Stephanelytron redcliffense Sarjeant, 1961a 
Plate 14, figure 6 


238 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


t960c Organism A. Sarjeant, 404, pl. 13, fig. 13, table 2. 

1961a Stephanelytron vedcliffense Sarjeant, 109-110, pl. 15, fig. 11, text-figs Io, 15. 
1962a S. vedcliffense Sarjeant; Sarjeant, table 4. 

1962b S. vedcliffense Sarjeant; Sarjeant, 495, pl. 70, fig. 7, tables 2-3. 

1964 S. vedcliffense Sarjeant; Downie and Sarjeant, 146. 

1964 S. vedcliffense Sarjeant; Sarjeant, table 4. 

1967 _ S. vedcliffense Sarjeant; Brito, pl. 2, fig. 3. 

1968b S. vedcliffense Sarjeant; Sarjeant, 225, pl. 3, fig. 5, table 2A. 


Description: The cyst is broadly ovoidal, rounded at both ends. The tubular 
processes extend down the flanks in six rows and surround the apex and antapex 
in transverse rows; there is also a median transverse row of processes. A corona, 
broad-based and bearing striations, is present on the antapex. The cyst wall is 
composed of two layers; both are thin and transparent, without ornamentation. 
The periphragm forms the processes. There is no connection between the central 
cavity and the cavity of processes. An apical archaeopyle is typically developed. 


FIGURED SPECIMEN: BM(NH) slide V.56366(1), sample BN 179, from the Cymodoce 
Zone of Benerville, Normandy. 


DIMENSIONS: Figured specimen: cyst length 4ou, breadth 32y, process length 5y, 
corona length 8. Range: length 40-60u, length (apex lacking) 45-5o0y, breadth 
32-45p, process length 4-5u, corona length 5—8y. Measured specimens 4 in number. 
Holotype dimensions, as given by Sarjeant: length 36, breadth 30y, process length 
5u, corona length Iou. The Kimmeridgian specimens exhibit similar dimensions, 
except in the length of the corona, which is greater in the holotype. 


REMARKS: This species was originally recorded from the Oxford Clay of England, 
and later from the Lower Oxfordian of Normandy, by Sarjeant (1961, 1968). Five 
specimens, all from the same horizon in the Cymodoce Zone of Normandy, were 
observed, which are closely similar to those figured by Sarjeant. 


Stephanelytron cf. redcliffense Sarjeant, 1961a 
Plate 14, figure 7 


DESCRIPTION: Two specimens, also from the Cymodoce Zone, show a general 
resemblance to S. vedcliffense but differ in that the processes are markedly thinner. 
Forms of intermediate character were not encountered. 


FIGURED SPECIMEN: BM(NH) Slide V.56365(2), sample BN 179 from the Cymodoce 
Zone of Benerville, Normandy. 


Dimensions: Figured specimen: cyst length (apex lacking) 35y, breadth 30u, 
process length 5, corona length 72. The second specimen could not be measured 
because of its bad preservation and orientation. 


REMARKS: These two specimens from the Lower Kimmeridgian (Cymodoce 
Zone of France) may represent a new species or might be extremes in the range of 
morphological variation of S. redcliffense. Fuller information must be awaited. 


FROM ENGLAND, SCOTLAND AND FRANCE 239 


Cyst-Family ENDOSCRINIACEAE Vozzhennikova, emend. Sarjeant and Downie, 
1966 


Genus ENDOSCRINIUM Klement, 1960b emend. Vozzhennikova, 1967a 
Endoscrinium sp. 
Plate 14, figures 9-11, text-figure 26 


DEscrIPTION: A species of Endoscrinium possessing a subspherical to broadly 
ovoidal periblast, without apical or antapical horns. The periphragm is irregularly 
studded with pores of varying shapes and sizes; the endophragm is finely granular. 
The sutural crests are well defined, in the form of low ridges. Reflected tabulation: 
4’, 6”, 6c, 5’”, Ip, pv, 1’’’’ and 8s. Plate 1’is elongate, plates 2’ and 3’ are relatively 
small, the boundary between them was not confirmed; plate 4’ is quite large. The 
precingular plates and postcingular plates are large, plate 3’’’ being the largest of all 
the plates. The cingulum is strongly laevorotatory, occupied by six plates; plates 1c 
and 6c are greatly reduced, the other cingular plates are of constant size. The 
cingulum divides the cyst more or less equally. The sulcus is broad, occupied by 
sulcal plates of varying shape and size. 

A precingular archaeopyle is developed, and formed by loss of plate 3”. 


FIGURED SPECIMEN: BM(NH) slide V.56369(1), sample OF 485, from well-bedded 
calcilutite, Montard d’Oignon, France. Lower Kimmeridgian (Mutabilis Zone). 


Dimensions: Figured specimen: overall length 78u, breadth 75u, endoblast length 
60u, breadth 55w. 


REMARKS: Only one well preserved specimen has so far been observed. The 


Fic. 26. Endoscrinium sp. Tabulation and the archaeopyle formation: left, in ventral 
view; right, in dorsal view. Specimen BM(NH) slide V.56369 (1). x c.836. 


240 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


perforation of the periblast and the presence of sulcal plates distinguish this species 
from all described forms. The general appearance of the cyst and the tabulation 
are most comparable to E. luridum, suggesting a relationship between two species. 


Cyst-Family HEXAGONIFERACEAE Sarjeant & Downie, 1966 
Genus HEXAGONIFERA Cookson and Eisenack, 1961a emend. Cookson and 
Eisenack, 1962 
Hexagonifera jurassica sp. nov. 
Plate 14, figures 5, 8 
1970 Hexagonifera sp. Gitmez, 2, pl. 1, fig. 12, table 4. 


DERIVATION OF THE NAME: So named because this is the first species of the genus 
observed in Jurassic assemblages. 


Dracnosis: A species of Hexagonifera with broadly ovoidal to elongate cyst. The 
periblast has a blunt, hollow apical projection formed by the periphragm only. The 
surface of the periblast is delicate, smooth or minutely granular: the endoblast, in 
contrast, is thick-walled and densely granular, with occasional tubercles. A circular 
cingulum divides the periblast almost equally; sometimes the epitract is slightly 
smaller than the hypotract. There is no definite indication of tabulation or of a 
sulcus. An apical archaeopyle is typically developed. 


Horotyre: I.G.S. slide PK.123, sample WB 20, from H.M. Geological Survey 
Borehole, Warlingham, at 2510 ft depth. Middle Kimmeridgian (Wheatleyensis 
Zone). 


PARATYPE: BM(NH) slide V.53621(1), sample SS 627, from 100 ft above the second 
dolerite sill, Staffin Bay, Skye. Lower Kimmeridgian (Baylei Zone). 


Dimensions: Holotype: overall length 85u, breadth 72p, endoblast length 73y, 
breadth 66u, Paratype: overall length (apex lacking) 46, breadth 50u, endoblast 
length (apex lacking) 40u, breadth 42u. The size range of specimens from different 
horizons is shown in Table 1; according to these measurements, the Lower Kim- 
meridgian specimens are smaller than those from the Middle and Upper Kimmeridgian. 
(There is only a slight size difference between the Middle and Upper Kimmeridgian 
specimens). No dimensional difference was observable between the English and 
French specimens. 


OBSERVED RANGE: Lower to Upper Kimmeridgian (Baylei to Pallasioides). Not 
yet observed from the Cymodoce, Mutabilis, Elegans and Scitulus Zones. 


Description: The subspherical to ovoidal endoblast is completely enclosed by the 
delicate periblast. The epitract of the periblast is conical, with no apical projection 
superimposed on the cone shape. The epitract of the endoblast is rounded and 
dome-shaped. The antapex of both periblast and endoblast is rounded. A poly- 
gonal apical archaeopyle is usually present ; generally the operculum remains attached 
to the shell. The tabulation is generally indeterminable, but the dorsal tabulation 


FROM ENGLAND, SCOTLAND AND FRANCE 241 


could be distinguished with difficulty on some specimens: two apical, three pre- 
cingular, three postcingular and one antapical plates were recognised. 


REMARKS: This new species is distinguished from previously described species of 
the genus by the presence of a cingulum and poorly developed tabulation. 

These specimens are similar to H. chlamydata Cookson & Eisenack, (1952) in 
having a granular endoblast, but it is impossible to compare the periblast since it is 
usually badly preserved or not preserved at all. The presence of a slight apical 
prominence, a cingulum and poorly developed tabulation distinguish this species 
from H. chlamydata. 


TABLE 2 
Range of the dimensions of Hexagonifera jurassica from the different levels of the 
Kimmeridgian 
Lower Middle Upper 
Kimmeridgian Kimmeridgian Kimmeridgian 
Periblast: 
Length 45-50. 70-102. 80-105u 
Length without apex 42-55 60-75. 55-70 
Breadth 35-50u 58-90 50-90 
Endoblast: 
Length 40-48u. 58-88. 65-90u. 
Length without apex 38-59. 55-75u. 45-05 
Breadth 35-52 58-75u. 45-75v 
Measured specimens I2 29 19 


Cyst-Family MUDERONGIACEAE Neale & Sarjeant, emend. Sarjeant & Downie, 
1966 
Genus MUDERONGIA Cookson & Eisenack, 1958 
Muderongia simplex Alberti, 1961 


Plate 15, figures 1-2 


1961 Muderongia simplex Alberti, 12, pl. 2, figs 1-6, pl. 12, figs 1-2, table c. 
1964 MM. simplex Alberti; Downie & Sarjeant, 134. 

1964 WM. simplex Alberti; Eisenack, 525-6. 

1966b M. simplex Alberti; G. & M. Deflandre, fiches 3249-50. 

1967b M. simplex Alberti; Sarjeant, table 12. 


DEscRIPTION: The cyst is flattened, bearing an apical, two lateral and two 
antapical horns. Its outline is almost rhombic, as a result of differential development 
of the horns. The lateral horns are short and rounded at their free end. The anta- 
pical horns are unequal in length; one of them is very short and blunt, the other is 
well developed. The endoblast lies close to the outer margin of the periblast, 
generally stretching out into the horns but not reaching their tips, so that lateral, 


242 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


apical and antapical pericoels are present. The tabulation is not well indicated 
but lines on the epitract, observable only with difficulty, simulate plate boundaries. 
A narrow cingulum is present but poorly marked. Both periphragm and endo- 
phragm are transparent; the surface of the periblast is granular. A well-developed 
apical archaeopyle was observed in one of the specimens; the other specimens ob- 
served often have a split on the flank of the apical region, indicating that the archaeo- 
pyle has not developed fully. 


FIGURED SPECIMENS: I.G.S. slides PK.128 and PK.129, sample WB 29, from 
H.M. Geological Survey Borehole, Warlingham, Surrey, at 2285 ft 7in. depth. Upper 
Kimmeridgian (Rotunda Zone). 


Dimensions: Range of the observed specimens (II in number): overall length 
78-110u, breadth 68—goy, endoblast length 65-88y, breadth 55-75u, overall length 
(without apex) 70, endoblast length (without apex) 48u. Alberti gave the following 
ranges from Cretaceous specimens of the species: overall length 68-175u, breadth 
63-133u- 

REMARKS: M. simplex has been recorded from Valanginian to Barremian of Poland, 
Bulgaria and Germany. Eleven specimens were recorded, for the first time from 
England and the Jurassic, all from one horizon, the Rotunda Zone of the Warlingham 
Borehole. These specimens are similar to the specimens figured by Alberti, the only 
difference being that the apical horn is not so long as the apical horn of previously 
recorded specimens and the notches at the ends of the lateral horns were not seen on 
the Kimmeridgian specimens. With its second, blunt antapical horn, M. simplex is 
similiar to the type species of the genus, M. mcwhaet, but it differs in its short and 
rounded-ended lateral horns, whereas those of the type species are long and curved, 
downwardly directed. 


Cyst-Family NELSONIELLACEAE Eisenack, emend. Sarjeant & Downie, 1966 
Genus SCRINIODINIUM Klement, 1957 
Scriniodinium bicuneatum (Deflandre) Sarjeant, 1967a 
Plate 15, figure 4 


1938 Palaeoperidinium bicuneatum Deflandre, 180, pl. 8, fig. 7. 
1957 PP. bicuneatum Deflandre; Downie, 422, pl. 20, fig. 2, table r. 
1964 P. bicuneatum Deflandre; Downie & Sarjeant, 137. 

1964 PP. bicuneatum Deflandre; Eisenack, 591-2. 

1964 FP. bicuneatum Deflandre; Sarjeant, table 2. 

1967a Scriniodinium bicuneatum (Deflandre) ; Sarjeant, 248. 

1967b S. bicuneatum (Deflandre) ; Sarjeant, table 11. 

1970 S. bicuneatum (Deflandre) ; Gitmez, 308, pl. 5, fig. 5, table 4. 


OBSERVED RANGE: Lower to Upper Kimmeridgian (Baylei to Pallasioides). Not 
yet recorded from the Elegans and Scitulus Zones. 

TOTAL KNOWN RANGE: Oxfordian (prob. Cordatum)—Kimmeridgian (Rotunda). 

FIGURED SPECIMENS: BM(NH) slide V.56370, sample MR 547, from the lower 


FROM ENGLAND, SCOTLAND AND FRANCE 243 


boundary of the Platynota Zone (Baylei Zone), west side of the Ravin d’Enfer, 
Crussol, France. 


DIMENSIONS: Range: overall length 80-115u, breadth 65-100, endoblast length 
75-90, breadth 62-83u. (Measured specimens 36 in number). Holotype dimen- 
sions, as given by Deflendre, are 1oou length, 65 breadth, well within the quoted 
range. 


REMARKS: S. bicuneatum was originally recorded from the Oxfordian of Normandy; 
the species was based on a single specimen which was not well preserved. In 1957, 
it was, for the first time, observed in the English assemblages, when Downie recorded 
it from the Pectinatus Zone of Dorset. His specimens also were poorly preserved. 

It is abundantly present in the Kimmeridgian samples examined from England 
(55 Specimens being recorded); but rare in Scottish and French assemblages (5 
specimens from the Baylei Zone of France and only one from the Cymodoce Zone of 
Scotland). The preservation was generally not good. The presence or absence of 
an endoblast was not confirmed by Deflandre, nor later by Sarjeant, who re-examined 
the holotype, noted the general similarity to the members of Scrimiodinium and 
redesignated this species as S. bicuneatum: its presence can now be confirmed. 

The authors consider that Deflandre’s figures are in an inverse orientation, with 
antapex uppermost. The figured specimen is shown in the correct orientation: 
the ventral tabulation is not discernible, but apical, pre- and postcingular plate series 
can be distinguished without difficulty. 


Scriniodinium dictyotum Cookson & Eisenack, 1960a 
Plate 15, figures 5-7, Plate 16, figure 6; text-figure 27 


1960a Scriniodinium dictyotum Cookson & Eisenack; 248-9, pl. 37, figures 8, 9. 
1962a S. dictyotum Cookson & Eisenack: Sarjeant, 262, pl. 1, fig. 9, tabs 3-4. 
1962b S. dictyotum Cookson & Ejisenack: Sarjeant, pl. 69, fig. 11. 


1964 S. dictyotum Cookson & Eisenack: Downie & Sarjeant, 145. 

1964 S. dictyotum Cookson & Eisenack: Eisenack, 755. 

1964a S. dictyotum Cookson & Eisenack: Sarjeant, table 2. 

1967 S. dictyotum Cookson & Eisenack: Sarjeant, table 11. 

1968 S. dictyotum Cookson & Eisenack: Sarjeant, 236, pl. 1, fig. 7, table 2b. 

1970 S. dictyotum Cookson & Eisenack: Gitmez, 310. 

1970 S. dictyotum subsp. dictyotum Cookson & Eisenack: Gitmez, 310. 

1970 S. dictyotum subsp. osmingtonensis Gitmez, 310-11, pl. 1, fig. 3, pl. 8, fig. 12. 

1970 S. dictyotum subsp. papillatum Gitmez, 311, pl. 9, fig. 11. 

1970 S. dictyotum subsp. pyvum Gitmez, 311-13, pl. 13, figs 1-2, pl. Io, figs 1: Text-fig. 33a—b. 


Remarks: A text-figure clarifying the differences (in form of the apex) between the 
four subspecies distinguished by Gitmez (1970) is here presented. The typical 
subspecies, S. dictyotum dictyotum, was not encountered in the basal Kimmeridgian, 
although recorded by Sarjeant (1962a, 1962b, 1964a, 1967b) from the Oxfordian of 
England and France: four specimens were, however, obtained from the Pectinatus 
Zone (specimen ED 240) of Dorset. The other subspecies were found only in the 
Lower Kimmeridgian: observed ranges: 


244 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


S. dictyotum osmingtonensis Baylei only: Dorset. 
S. dictyotum papillatum Baylei to Mutabilis: Dorset and France. 
S. dictyotum pyrum Baylei only: Dorset and France. 


d / 
S.dictyotum subsp. papillatum 


S. dictyotum subsp. osmingtonensis 
alin : S.dictyotum subsp. dictyotum S. dictyotum subsp. pyrum 


Fic. 27. Scriniodinium dictyotum (Cookson & Eisenack). Diagram showing the variation 
in the character of the apex in the four subspecies of the above. 


Scriniodinium sp. 
Plate 13, figure 4 


Description: The periblast is broadly ovoidal, with a hollow apical horn and 
rounded antapex. The surface of the periblast is smooth. The endoblast is sub- 
spherical to elongate, with rounded ends; its surface is smooth or minutely granular. 
Boundaries of reflected plates were indicated very feebly or not at all; in consequence, 
the tabulation could not be determined. The cingulum is relatively narrow and 
slightly helicoid, laevorotatory. A broad sulcus could be distinguished on some of the 
specimens observed. No archaeopyle was seen. 


FIGURED SPECIMEN: I.G.S. slide PK.107, sample WB 7 from H.M. Geological 
Survey Borehole, Warlingham, Surrey, at 2834 ft 7in. depth. Lower Kimmeridgian 
(Eudoxus Zone). 


DIMENSIONS: Figured specimen: periblast length 105y, breadth 76y, endoblast 
length 80u, breadth 7ou. Range: overall length 53-105u, breadth 42-76y, endo- 
blast length 42-80u, breadth 35~7ou. Measured specimens 5 in number. 


OBSERVED RANGE: Lower to Upper Kimmeridgian (Mutabilis to Pectinatus). 


REMARKS: Six specimens [two from the Lower Mutabilis, two from the Middle 
(Scitulus) and two from the Upper (Pectinatus) Kimmeridgian], all from English 
assemblages, were recorded. In general appearance, they are similar to Dingodinium 
curopaeum, which was recorded from the Aptian of Germany by Eisenack (1958c). 
However, these specimens are larger; Eisenack did not record specimens over 
65-67u length. Since there is a very considerable stratigraphic gap and also a 
difference in dimensions, and in the absence of data regarding the archaeopyle, they 
were not placed in D. ewropaeum but were assigned to the genus Scriniodium. 


FROM ENGLAND, SCOTLAND AND FRANCE 245 


Genus SIRMIODINIUM Alberti, 1961 
Sirmiodinium grossi Alberti, 1961 
Plate 16, figures 7-8 


1961 Sivmiodinium grossi Alberti, 22, pl. 7, figs 5-7, pl. 12, fig. 5; table c. 
1964 S. gvossit Alberti; Downie & Sarjeant, 145. 

1965 S. gvossi Alberti; G. & M. Deflandre, fiches 2787-2788. 

1966 S. gvossi Alberti; Sarjeant, p. 212, pl. 22, fig. 7, table 5. 

1967b S. gvossi Alberti; Sarjeant, table 11. 


DeEscripTION: The cyst is dorso-ventrally flattened. The periblast is roughly 
pentagonal in shape, with a blunt apical horn and flattened antapex. The endo- 
blast is subspherical to ovoidal, both ends rounded. The circular cingulum is very 
deep and divides the cyst unequally ; the epitract is smaller than the hypotract. The 
tabulation is poorly indicated; on the dorsal side of the cyst, two apical, three pre- 
cingular and three postcingular plates were recognised, but the ventral tabulation 
was not established. The surface of the endoblast is apparently smooth, the surface 
of the periblast minutely granular. In one of the five specimens observed, an apical 
archaeopyle was observed, formed by loss of the whole apex; in the other specimens, 
the apex is still attached to the shell in the position of the first apical plate and a 
median dorsal, precingular plate (possibly 3’’) is also surrounded by splits, suggesting © 
that a combination archaeopyle of an undescribed type is developed. In all the 
observed specimens there is a posterior dorsal aperture of circular shape. 


FIGURED SPECIMENS: BM(NH) slide V.56373(1) and V.56374(1), sample CP 245, 
from the Rotunda Nodule Bed, Chapmans Pool, Dorset. Upper Kimmeridgian 
(Rotunda Zone). 


DIMENSIONS: Range: overall length 65-80u, length without apex 48y, breadth 
48-70u, endoblast length 59-70u, without apex 43u, breadth 40-60n. Measured 
specimens 5 in number. Holotype: overall length gtu, breadth 86u, endoblast 
length 72y, breadth 61, as given by Alberti. 


OBSERVED RANGE: Upper Kimmeridgian (Rotunda Zone). 
TOTAL KNOWN RANGE: Upper Kimmeridgian (Rotunda Zone) to Upper Barremian. 


REMARKS: Five specimens were observed, all from the same horizon in Dorset. 
These specimens are characterized by their archaeopyle formation and their posterior 
dorsal aperture. Alberti (1961) recorded the holotype from the Upper Hauterivian 
to Upper Barremian of Germany, Sarjeant (1966) encountered it also in the Lower 
Hauterivian. Its presence also in the Upper Jurassic suggests a direct relationship 
with Scriniodinium, from which it may well have evolved by enlargement of the 
archaeopyle. 


Cavate cyst sp. indet A 
Plate 16, figure 3 


DEscRIPTION: The periblast is broadly ovoidal, with a well developed anterior 


246 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


= 


pericoel. The endoblast is spherical. There are no apical or antapical projections; 
tabulations is not indicated. The relatively narrow cingulum divides the cyst 
unequally; the epitract is longer than the hypotract. The surface of the periblast is 
perforated; the endoblast has a granular surface. An archaeopyle was not observed. 


FIGURED SPECIMEN: I.G.S. slide PK.102C, sample WB 2, from H.M. Geological 
Survey Borehole, Warlingham, Surrey, at 2959 ft 5in. depth. Lower Kimmeridgian 
(Mutabilis Zone). 

Dimensions: Figured specimen: periblast length 63, breadth 52u, endoblast 
length 48y, breadth 4Qu. 

RemMARKS: This observation was based on a single specimen. In its general shape, 
it looks similar to members of Deflandrea and Hexagonifera, but an archaeopyle was 
not observed. It may represent a new genus, but before this can be decided, better 
preserved specimens must be awaited. 


Cavate cyst sp. indet. B 
Plate 16, figures 2, 4 


DESCRIPTION: The cyst is broadly ovoidal to elongate in shape, bearing a short, 
blunt, hollow apical horn, and one or two antapical horns. The endoblast is sub- 
spherical to spherical, with rounded ends. Tabulation and sulcus are not indicated. 
The broad cingulum divides the cyst unequally: the epitract is longer than the 
hypotract. The periphragm is densely perforated. The endophragm is smooth or 
minutely granular. An irregular breakage on the epitract, suggesting the beginning 
of opening of an apical or intercalary archaeopyle, was observed in some of the 
specimens. 


FIGURED SPECIMENS: I.G.S. slide PK.104, sample WB 4, from Warlingham 
Borehole at 2910 ft 6 in. depth; and I.G.S. slide PK 106, sample WB 5, from the 
Borehole at 2885 ft 1 in. depth. Lower Kimmeridgian (Eudoxus Zone). 


DIMENSIONS: Range (22 specimens were measured) : overall length 45-70u, breadth 
33-60u, endoblast length 33-53y, breadth 31-5ou. 


REMARKS: A group of specimens (44 in number), all from the Lower Kimmeridgian 
(Mutabilis to Pectinatus) of the Warlingham Borehole, were recorded which resemble, 
in their general appearance (with apical and antapical projections) the species of the 
genus Deflandrea. However, since no regular archaeopyle formation was observed, 
they are not attributed to that genus: they may indeed well be representatives of a 
new genus. The cavate cyst sp. indet. A (previously mentioned) shows similarities 
to these specimens, in their perforated periphragm and similar overall appearance, 
but has no projections at the apex and the antapex. 


FROM ENGLAND, SCOTLAND AND FRANCE 247 


INCERTAE SEDIS 
Group ACRITARCHA Evitt, 1963 
Subgroup ACANTHOMORPHITAE Downie, Evitt & Sarjeant, 1963 
Genus MICRHYSTRIDIUM Deflandre, emend. Sarjeant, 1967c 


Micrhystridium recurvatum Valensi, 1953 
Plate 17, figures 1-2 


1953 Micrhystridium vecurvatum Valensi, 43, pl. 6, figs 1-4, pl. Io, fig. ro. 
1955 WM. vecurvatum Valensi; Valensi, 589, pl. 1, fig. Io. 

1960c M. vecurvatum Valensi; Sarjeant, 392, pl. 14, fig. 19, text-fig. 1a, table 2. 
1962b M. rvecurvatum Valensi; Sarjeant, 489, text-figs 8b, f, tables 2-3. 
1963 MM. vecurvatum Valensi; Wall & Downie, 778. 

1964 M. vecurvvatum Valensi; Downie & Sarjeant, 133. 

1964 MM. vecurvatum Valensi; Sarjeant, table 4. 

1964 IM. vecuvvatum Valensi; Gocht, 123, pl. 16, fig. 13, text-fig. 43. 
1965b M. vecurvatum Valensi; G. & M. Deflandre, fiches 2346-2351. 

1965 MM. vecurvatum Valensi; Sarjeant, 177-178, pl. 1, figs 11-18, table 1. 
1967 M. vecuvvatum Valensi; Dodekova, 27, pl. 3, fig. 10, table 1. 

1967c M. vecuvvatum Valensi; Sarjeant, pl. 1, figs 1, 3-5, 9, text-fig. 1H. 
1968 MM. vecurvatum Valensi; Sarjeant, table 2A. 


DEscRIPTION: The cyst is spherical to subspherical, bearing simple, hollow, 
distally closed, curved processes, about 32-38 in number. The surface of the cyst 
is smooth or very finely granular. 

FIGURED SPECIMEN: I.G.S. slide PK.127, sample WB 26, from H.M. Geological 
Survey Borehole, Warlingham, Surrey, at 2359 ft gin. depth. Upper Kimmeridgian 
(Pectinatus Zone). 

Dimensions: Figured specimen: diameter Iou, process length 4u. Range: dia- 
meter 13-20u, process length 3-124, measured specimens 29 in number. Valensi 
gave the holotype diameter as Ion, Sarjeant gave the mean diameters of the speci- 
mens from Normandy as 14y. In contrast, Dodekova gave the average diameters 
of her Kimmeridgian specimens from Bulgaria as 22u; these specimens appear well 
outside the normal size range and may well represent a distinct species. 

OBSERVED RANGE: Lower to Upper Kimmeridgian (Cymodoce to Rotunda). Not 
yet observed from the Elegans and Scitulus Zones. 


TOTAL KNOWN RANGE: Bajocian to Upper Kimmeridgian (Rotunda Zone). 


Micrhystridium sp. 
Plate 17, figures 7-8 
1970 Micrhystridium inconspicuum Gitmez, pl. 1, fig. 8, table 4. 


DescripTion: A form of Micrhystridium having a spherical shell, with thick shell 
wall (c. In). Processes are simple, conical, about 30 in number, and slightly curved. 


248 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


The length of the processes is not more than one quarter of the shell diameter; they 
are hollow, distally closed, their cavity connected to the shell interior. The surface 
of the shellis smooth. An opening in the form of a split was observed in the single 
specimen seen. 


FIGURED SPECIMEN: BM(NH) slide V.53953(1), sample OM 418, from 10 ft above 
the Ringstead Coral Bed, Osmington Mills, Dorset. Lower Kimmeridgian (Baylei 
Zone). 


DIMENSIONS: Figured specimen: shell diameter Ig x 20u, process length 4—5y. 


REMARKS: A single specimen recorded from the Baylei Zone of Dorset, was 
earlier placed into M. inconspicuum (Gitmez, 1970); subsequently, examination by 
high power objective has shown that it is different from M. inconspicuum as recently 
redefined by Deflandre and Sarjeant (1970). 

With its short processes, this specimen is similar to the Oxfordian species M. 
vavrispinum Sarjeant (1960c). However, its cyst diameter is greater than that of 
M. varispinum and its processes are slightly longer and more numerous (Sarjeant 
gave the cyst diameter of the latter species as IIp, process length 2-2-5 and the 
process number as 14-20). It may represent a new species, but more specimens must 
be awaited. 


Genus SOLISPHAERIDIUM Staplin, Jansonius & Pocock, 1965 emend. Sarjeant, 
1968b 
Solisphaeridium claviculorum (Deflandre) Sarjeant, 1968b 
Plate 17, figures 9-10 


1938e Hystrichosphaeridium claviculorum Deflandre, 191-2, pl. 10, fig. 4. 

1963 Baltisphaeridium claviculorum (Deflandre); Downie & Sarjeant, 9r. 

1964 B. claviculorum (Deflandre); Downie & Sarjeant, 88 

1964 8B. claviculoyrum (Deflandre) ; Sarjeant, table 3. 

1966 B. claviculovrum (Deflandie); Davey, Downie, Sarjeant & Williams, 174. 

1968 ?Solisphaeridium claviculorum (Deflandre) ; Sarjeant, 233, pl. 2, figs 13, 15, table 2A. 
1970 S. claviculovrum (Deflandre); Deflandre & Sarjeant, 6, pl. 1, fig. 5. 


DESCRIPTION: Cyst spheroidal, moderately thin-walled, bearing about 22 processes. 
These processes are simple and straight, their length about four-fifths of the cyst 
diameter; they are closed at both the distal and the proximal ends but contain an 
elongate cavity which does not connect to the central cavity of the shell. The surface 
of the cyst is finely granular. An opening, in the form of a split, was observed. 

FIGURED SPECIMEN: I.G.S. slide PK.101, sample WB1, from H.M. Geological 
Survey Borehole, Warlingham, Surrey, at 2984 ft 7in. depth. Lower Kimmeridgian 
(Mutabilis Zone). 

DIMENSIONS: Shell 18 x 20, process length 17u. Holotype: overall diameter 
58u, process length 14-16y (as given by Deflandre). 

Remarks: A single specimen of this species was originally recorded from the Upper 
Jurassic of France and attributed to the genus Hystrichosphaenidium. In 1963, 


FROM ENGLAND, SCOTLAND AND FRANCE 249 


Downie and Sarjeant transferred it to the genus Baltisphaeridium on the basis of its 
spine characters. Recently, one of the authors (W.A.S.S., 1968b), after re-examina- 
tion of the holotype and recording further specimens from the Lower Oxfordian, 
placed this species in the genus Solisphaeridium hesitantly, because of the absence of 
clear knowledge of the mode of archaeopyle formation. Subsequent study of the 
holotype has since confirmed his judgement (Deflandre and Sarjeant, 1970). 

A single specimen was observed in the Warlingham Borehole sample from the 
Mutabilis Zone which conforms in morphology to this species; since only one speci- 
men was found, the presence of the species at this level, after such a stratigraphic 
hiatus, cannot be regarded as definite since pollution cannot be altogether ruled out. 


Subgroup NETROMORPHITAE Downie, Evitt & Sarjeant, 1963 
Organism A 
Plate 16, figure 1; plate 17, figure 3 
1970 Organism A Gitmez, 321, pl. 11, figure 9, table 4. 


DEscriPTION: The cyst is ellipsoidal to elongate. One pole is rounded, the other 
is flattened: the lateral walls are slightly outbowed. The cyst wall is thick (about 
Iu), without ornamentation, processes or division into fields. The surface is smooth 
but porate; distribution of the pores is irregular, being generally densest around the 
flattened pole and on the sides of the cyst. An opening was observed in the flattened 
pole: its outline appears to be roughly circular. 


FIGURED SPECIMEN: BM(NH) slide V.53948(3), sample RB 219, from the Rhactor- 
hynchia inconstans Bed, Ringstead Bay, Dorset, Lower Kimmeridgian (Baylei Zone). 

DIMENSIONS: Figured specimen: cyst length 77y, breadth 28u. Range: length 
42-77, breadth 18-48. Measured specimens 12 in number. 

REMARKS: This new form was observed in the assemblages from the Baylei and 
Mutabilis Zones of Dorset and Le Havre only. It resembles in general outline mem- 
bers of the genus Palaeostomocystis, especially the species P. laevigata Drugg, 1967 
(Upper Cretaceous of California): but none of the specimens observed contains an 
internal cyst or sac-like body. 


Subgroup PTEROMORPHITAE Downie, Evitt & Sarjeant, 1963 
Genus PTEROSPERMOPSIS W. Wetzel, 1952 
Pterospermopsis harti Sarjeant, 1960c 
Plate 17, figure 6 


1960c Ptervospermopsis harti Sarjeant, 402-3, pl. 14, fig. 16, text-fig. 3, table 2. 
1962b P. harti Sarjeant; Sarjeant, table 3. 
1964 PP. harti Sarjeant; Downie & Sarjeant, 143. 


FIGURED SPECIMEN: I.G.S. slide PK.111, sample WB 8, from H.M. Geological 
Survey Borehole, at 2810 ft 6 in. depth. Lower Kimmeridgian (Eudoxus Zone). 


250 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


DIMENSIONS: Figured specimen: overall 30 x 30u, cyst 12 X I2u. Overall 
dimensions of the other English specimen 32 x 32u, cyst 17 x 17u. French 
specimen: overall 30 x 30y, cyst I2 X I2u. 

OBSERVED RANGE: Lower to Upper Kimmeridgian (Eudoxus to Pectinatus). 
(See below.) Total Known Range: Upper Oxfordian (Pseudocordata) to Upper 
Kimmeridgian (Pectinatus). 

REMARKS: This species was originally recorded from the Corallian of Yorkshire. 
It is veryrare in the Kimmeridgian, only threespecimens being recorded, one eachfrom 
France (Mutabilis), Warlingham Borehole (Eudoxus) and Dorset (Pectinatus Zone). 


Subgroup UNCERTAIN 
Acritarch sp. indet. 
Plate 17, figures 4-5 


DEscRIPTION: The cyst is elongate, ovoidal with rounded ends, bearing about 
I4-16 processes. These processes are simple, straight or slightly curved, conical 
and closed distally. The shell wall is composed of two layers, the outer layer 
forming the processes; the processes are hollow but their cavities are not in contact 
with the central cavity. The surface of the cyst is smooth or minutely granular. 
An irregular opening was observed. 

FIGURED SPECIMENS: I.G.S. slides PK.125 and PK.126, sample WM 26, from 
H.M. Geological Survey Borehole, Warlingham, Surrey, at 2359 ft 9 in. depth. Upper 
Kimmeridgian (Pectinatus Zone). 

DIMENSIONS: Range: Shell length 15-35y, breadth 8-15, process length 6—1oy. 
Measured specimens 5 in number. 

REMARKS: All the specimens were recorded from the same horizon in the Warling- 
ham Borehole (Pectinatus Zone). They differ from described species in their 
elongate shape and irregular opening. They may represent a new species and perhaps 
even a new genus. 


IV. STRATIGRAPHICAL DISTRIBUTION CHARTS 
See Tables 3 to 6. 


V. CONCLUSIONS 


In the Kimmeridgian samples from England, Scotland and France described 
by Gitmez (1970) and herein, 36 genera, comprising 110 species, of dinoflagellate 
cysts and 6 genera, comprising 16 species, of acritarchs were recognised. From 
these, two new genera, 23 new species and 4 new varieties have been proposed: more 
than a dozen other forms certainly represent new species but were not proposed as 
such, because of poor preservation or (more frequently) inadequate numerical repre- 
sentation. In addition, there was a further list of species, probably new, whose 
preservation, presentation or orientation entirely precluded their description: the 
microplankton of the Kimmeridgian Stage is thus much more rich and more varied 
than has hitherto been recognised. 


TABLE 3, \ 


‘The numerical distribution of microfossils inthe Kimmeridgi: i 
Cambridgeshire and Scotland (Staffin Bay na Canney alan casemsblates fromm Dorase Op ordste) 


DORSET 


CAM-| OXFORD- SCOTLAND 
BS. SHIRE 


Baylei Zone Autissio- 


2 Peetii 
agence 4 2 ‘ectinatus 
as 


4 
*4 ° 

Zone 28 
g 


ensis 
Zone 


+ Pallasioides Baylei EI 
he bylei 2 
Ea: Zone 

28 || Zone 5S 


Zone 


Wheatley- 
Hudlestoni 
=Pectin. 


OM 131 
OM 418 
OM 419 
OM 420 
HD 191 
RB 218 
KD 227 
CD 229 
CH 231 
RD 234 
FD 236 
ED 237 
ED 240 


LO 352 
LO 353 
LO 360 
SS 625 
SS 626 
SS 627 


Chytrocisphaeridia chytrocides: ar 17 % 16 - ‘ Teagieee «1g NCD 2” Pa agra 
€ mantelli ; 3 ee: $ e 

C. pococki F 

Chee Maecamonitd Siena EAGT gees dler es - ewer aie to en tice |e ak 
Tenua capitate “4 * 2 . q : 5 ci 7 2 : . . - - S 
1. echinata Owe ee a 3 +p ills 6 

T. hystnx it, a Bs EE wo Ke ig} eS Wat wees ere oilltallreecn oiling oc 
T. pilosa an ca te . : 5. Se 4 


tsp. 3 é 
‘Acanthaulax venusta . Or ec ) oe ae . . A op 6 8 ao 5 a tS 
Cry tarchaeodinium calcaratum { 5 y : 4 * , . . . : . - : (A t |} 5 
C cf. calcaratum, a ee Pee! co  p 8 Se gk OG 5 : 
Gonyaulacysta aculeata. ‘ . . . . . . 9 fs e ; 5 : 2 K 2 t 

G. angulasa : . . . : : i “ 

G, cauda 


ype 
+ 


cf, belicoides i cies a : : Is oC wo oe 2 ian So Ta ag 
hyaloderma ee ee a ee ee tee AAI colli Nl See et 
* jorassica 3) 13) (6) 20, (kao 163)» 1 is Oe ee, “ee allio eee es ctr ey 
jurassica var. longicornis ee es oo 1 5 ae 5 3 as, jae 

Jongicornis é 5 . 

5. ef, mamillifera Be hee rite oop 6 o : oop fied H Sh biat ie 
5. nuciformis ye Ey id ae Uh oes aU OG «SG Sows m SS A MD 4 ee (ik eg 
5. perforans Re od er ee as oes ee afr acre enn te wee II aie 

¥. serrata, 1 . - . . 2 a a ° FE 6 ' 
5. sp. A 

5. sp. D 

5. sp. E 

sp.G a ee i oO 2 : 
5. Sp. H . . . . . - . 8 . . 2 
Leptodinium aceras 4 A F c - : fi “ 
L. amabilis ee cohen “oe op eg >, gag aeons a eee) 
L. arcuatum 2 . . 1 . . z ‘ - . * - 

L. ef. crassinervum . . . : a . . = - . - . - . . = : 4 
L. egemenil im © % : 5 é 6 Wee we 
1. ef, subtile fc Paice Te ee G8 figs. AS 
L-sp. een he se 8G 5 5) Ge 2 - A a mw 6 
Occisucysta balios 
©. monoheuriskos fon 6 

©. sp. (Gitmez, 1970) Seg oF er te 4 ee | gon OG Pee oan BNI Wo oS Oe 
Belodinium dysculum + ee poo 23 3) ea oS ee ee eae cee Se HES NHI we see = A a 
Dictyopyxis areolata 2 : Flee foe cay ge 0 ee et Hie gee eee com Gu \ 


D. cf. reticulata . . : . - . . . . . t . , . 5 . : a o © 
Histiophora cf. ornata 6 “ SR OR eR ME RD ps 
Meiourogonyaulax dicryptos aac ec: f io) bo hs F 
M. pila 6 5 E 5 : 5 A o ‘ fd 5 3 
M. stafinensis Salou : =e : 3 
M. sp. A (Gitmez, 1970) 
M. sp. B, herein. a te Os oe tf 
Apteodinium granulatum ie ie ee sy eek a i 
A. cf, maculatum, ea eee mc ea. rc? | t r 93 aly pk Ree Serres, ||(hisy Saar 
Pareodinia ceratophora Aa | a Eo a a owe 2 a) | 20), ae eee ava, 
‘Trichodinium sp. Re ee! Mc oes ee aie wor oo eos a ee Al) | Se rete 
Imbatodinium antennatum 1 eS ae 2 
1. cf. villosum Be OE ai ge oe Cee ene eect res o>) |(| Ke memo | We on 
8 
1 


w 
wo 
—— 


Nannoceratopsis pellucida, yo ty ah tee at 1 
Egmontodinium polyplacophorum, a eo Ek Ss cat 
Proximate cyst sp. indet. Hela ieee Ro ee oe 
Heslertonia pellucida es in Wy ose aes 0 oe ae 
Epiplosphaera reticulospinosa tt ae eee eS ee ae oe i 8 Allis ao = yea OS 
Adnatosphaeridium paucispinum ee na ee cee ee ee eo : Sp gece 0 tee 
Cleistosphaeridium ehrenbergt 6 & Jan ot 2 : Se : 4 oe 

C. polyacanthum 1 ; 

C. polytrichum a Sanna 
€. tribuliferum 4 

C. sp. (Gitmez, 1970) 
C. sp., herein. . = > : q : : 
Hystrichosphaeridium petilum 5 5 Dass x. a > eee 
Oligosphaeridium pulcherrimum A 2 - 
Polystophanephorus sarjean| 

Prolixosphacridium ef, deirense 

P. granulosum 

P. parvispinum 

Systematophora arcolata 

S. orbifera 

5. ovata 

‘Taeniophora iunctispina é ‘ 
Stephanelytron cf. scarburghense 4 2 : ae Ry AS Ue Xa pay es : 
Endoserinium cf. campanula Fo Rr ad ; Be PSA TEE ° 

E. galeritum 
F. luridum A : ~ 5 Co ee 

E. oxfordianum + + “ : 0 cS 5 5 5 - = 5 * : - 
Psaligonyaulax apaleta a Ae co é ‘ : : : Ss S 
P. sp, (Gitmez, 1970) i 3 4 . 5 5 . - . . * a ire : ; ; 
Hexagonifera jurassica : e ci 5 5 D 8 eo ea 
Faryocavatus tuberous o * : . . . : 4 5 
Scriniodinium bicuneatum . 5 . : = . . ot as 

S. crystallinum S 4 n 4 - : | 

5. dictyotum subsp, dictyotum i " c a . x 5 . . . 

5, dictyotum subsp, osmingtonensis 
S, dictyotum subsp, papillatum 


Geet) 
ae 
w 


7 


fee || 2 || 


funn 
© 
Bn 


w 


wu 


microplankton 


raminiferal shell linings 


TABLE 4 


The ni i i 
je numerical distribution of microfossils in the Kimmeridgian assemblages from the Warlingham Borehole, Su rey 


Mutabilis 
Zone 


Scitulus Wheatleyensis Hudlestoni 
Zone Zone Zone 


Pectinatus Rotunda 
Zone Zone 


rensis 


ar 
—o Zone 2 Ie 


WB 
WB 
WB 3 
WB 4 
WB 5 
WB 6 
WB 
WB § 
WB 9 
WB 10 
WB 1 
WB i 
WB 13 
WB 14 
WB 15 
WB 16 
WB 17 
WB 18 
WB 19 
WB 21 
WB 22 
WB 23 
WB 24 
WB 25 
WB 26 
WB 27 
WB 28 


Chytrocisphaeridia chytrocides sh) om Ze <pl ey aan ay 
C. mantelli Sf ie a 
pococki 

Cramea warlinghamensis ee lee ; Nae B58 

Tenua capitata 4 : Dp eo : 

‘7. echinata ‘ . : if Be mS ry c 

T. hystrix Jb SO ae : j 1 50 chet i 

7. pilosa : 5 3 us 

Gonyaulacysta angulosa : F 7 Ps 5 2 é a 3 

G, cladophora ‘ . : , ‘ x H : , 6 4 % . 5 

ehrenbergii ¢ ; am oe 5 

ef, givseppei . 3 a 

_ globata “os 

granulata 1 i 

, granuligera eG : F ; 

jurassica ! t 2 

jurnssica var. longicornis : F I 

 longicornis Tia ar 

"cf, mamillifera ary 

nuciformis 6 : mas 

perforans : 

sp. B , ead r 

sp. C : 2 ip ar ce er 

G. sp. E he 8 5 ; 

Leptodinium aceras 5 Py 

L. arcuatum . 

L. sp. : A : S 1 

Occisucysta balios 2 TS : 

Histiophora cf. ornata 

Meiourogonyaulax pila . . 

M. staffinensis : ; I 

M.sp., herein Te 

‘Apteodinium granulatum ‘ f . t 

A-cf. maculatum : é 1 : 

Pareodinia ceratophora 5 uO me A ey 1 ri 7 

Imbatodinium antennatum 5 : 5 1 i 

Proximate cyst sp. indet, : 

Cleistosphaeridium ehrenbergi a gu 

C, polyacanthum 5 . 1 

© tibuliferam i my s M _ 5 : - 

C. sp,, herein Z 5 rae 1 we 1 ‘ ie | Oey 

Hystrichosphaeridium petilum : St siete hina ae: ae : 

Prolixosphaeridium granulosum : 1 a 5 ee rome 1 

P. parvispinum : : : 1 

Systematophora areolata 23 4 5 G 4 6 5 

S orbifera - Ze ‘ ; u 7 a c ) G4 a i Yin 2 é a 

Endoscrinium Turidum Sa Pe ef a5 > Pees : 

E. oxfordianum > 5 rs . = 2 2 2 : . 6 A : 

Psaligonyaulax apaleta 1 3 Beas I “ ‘ E eS Tes 

Hexagonifera jurassica fs 5 Tes 3 5 pas 1 o tb a oe oe a 

Parvocavatus tuberosus c 1 : ry . . . . 1 

Muderongia simplex E - Pe ; 

Scriniodinium bicuneatum , tee :  ankS Pee cy ra Oe ahs 7 

crystallinum, 1 

dictyotum subsp. papillatum ; 1 ; Pre a5 2 ee eee ee eee ee 

playfordi z 5 sii 1 any é [ie 

S. sp. 1 5 6 1 I Mer 8 1 

Netrelytron parum 

Cayate cyst sp. indet. A 

Cavate cyst sp. indet. B F 

Micthystridium fragile 66 
2 
7 


2 
e 
7B 
& 
3 


° 
ES 
Ges 
nanid 
ry 


G. 
G. 
G. 
G. 
G 
G. 
G 


o9900 
ee 


w 


w 
rear 


wR : I ya 
M. inconspicuum 

M. recuryatum 5 x ; 
M. sydus A i 1 é ee Oe as eae as j 5 I 
Solisphaeridium claviculoram og = : : : 
S. stimuliferum a We Oh Tk - ee : : 
Veryhachium hyalodermum 3 1 : : ap stig et 5 5 ok oy eo 
Pterospermopais australiensis 2 : 2 pees ; 3 é tee ae 
P, harti , : ww inad 2: 1 
Acritarch sp, indet. ears aes thaw " : oar am © oc 
Total number of determined microplankton 158 93 84 101 119 95 6x 40 43 81 47 32 tor 72 88 112 52 49 87 65 10 24 56 47 42 97 80 39 


Ria muctie 
© 
oe 
2 
r 


re) 


Indeterminate microfossils 40 15 25 16 17 7 48 6Y 57 18 22 17 108 33 117 45 106 50 118 153 20 32 53 34 7 201 27 27 
Foraminiferal shell linings Gy Rate eae) Ber XO: Ci BRP eye ie ee eae eee GREE S eae Ate st ok) Naw ea BS One 
Pollen & Spores 88 60 94 94 of 83 75 43 58 83 81 84 72 70 67 80 58 83 75 62 82 82 77 77 93 92 92 94 
Wood fragments ea 3 Toeegvenxdeeyes 2 31 os) i he a Ta Chas 7 he ke ¢ I 


185 290 286 113 145 188 172 143 209 200 161 


Torat 291 280 204 211 227 189 190 172 176 193 151 132 281 176 274 


- 


wine \ Sy 


TABLE 5 


‘The numerical distribution of microfossils in the Kimmeridgian assemblages from France 


Baylei Zone Cymodoce Autissiodorensis 


Zone Mutabilis Zone 


Zone 


Boulonnais J 
ura Mont 
Mountains, Crussol 


Normandy 

M. Crussol 

Normandy 

Lorraine 
oe 
Gz 
es 
2 

Le Havre 


CC 447 
CE 448 
CC 449 
CC 450 
CC 451 
CC 452 
CC 455 

184 


VN 
HE 185 
HE 186 
MR 547 
BN 179 
MR 548 
MR 550 
HF 395 
OF 485 
OF 486 
OF 487 
MR 552 
MR 553 

MR 554 

MR 555 


Zone 
Palla Zone 


Scitulus 
Jura M. 


Boulon, 


MV 489 


Chytroeisphacridia chytroeides 
C mantelli 

C. pococki D 1 
Tenua capitata f : 
T. echinata Coa at 5 A 1 3 

T. hystnx v ES 5 r 2 1 qq G aes 3 eB 7 
T. pilosa : Taree, WE ; 
Acanthavlax venusta . : ‘ 1 a és 

Cryptarchacodinium sp : 1 : 

Gonyaulacyata aculeata A 1 t 

angulosa . 1 1 1 1 

cauda 1 

cladophora 1 ‘ , 5 

ehrenbergit 2 1 ” - 2 
5. eisenacki 

cf. eisenacki 3 

cf. giuseppei 1 A 5 
granulata bo Bie fs : ce 1 5 
granuligera Tf ha ce) 6) Ge Ge ee 1 

cf, helicoidea : t 

hyaloderma f : 1 
jurassica 2 4 

jurassica var. longicornis 

longicornis 6 3 
cf, mamillifera 1 cae ae : 
nuciformis 1 + ck oe ip mo 2 4 
>. serrata 2 1 

>. systremmatos (ob 

5. sp. A uk 

Leptodinium amabilis 1 

L. arcuatum * 1 . . 1 1 

L. clathratum 4 1 : : 

L. egemenii 5 9 3 3 
L. ef. subtile ‘ ; 5 ae 1 
Occisucysta balios 1 : 1 (ee “ 
Dictyopyxis arcolata ch 1 2 Z 5 1 
D. cf. reticulata 5 1 ea 4 
Histiophora ef. ornata Lite 1 

Meiourogonyaulax dicryptos : = é , 

M. staffinensis 1 Oe Go 4 Lon a © 3 
Apteodinium granulatum 
A. cf. maculatum. 
Pareodinia ceratophora 
Imbatodinium antennatum - 1 . 5 

Heslertonia pellucida ses : ror 2 1 
Epiplosphaera reticulospinosa 
Adnatosphaeridium paucispinum ‘ E 2 9 : 
Cleistesphaeridium ebrenbergi Cie i | Taner cr zo o ae a 
C. polyacanthum: A 

C. tribuliferum. C Bhi hig 2 
C. sp. (Gitmez, 1970) : ried % ey x A 3 
Hystrichosphaeridium petilum hee 6 1 1 
Oligosphaeridium pulcherrimum : - 
Polystephanephorus sarjeantii 1 
Prolixosphaeridium granulosum. ce 5 : ee 5 moO 1 2 
Systematophora areolata 75 5 (9 bey FER SH c 51 6 6 1 3 1 34 2 6 
S. orbifera 33073) <5) 4 ay Ss 3 

Taeniophora iunctispina hati eS yo | Keke & oo) 

Stephanelytron redeliffense 5 

S. cf. redcliffense 

S, scarburghense anes ; 1 T 
Endoscrinium cf. campanula die eve fide 9) 

galeritum 2 > 

Juridum Hg E n t 2 : t 
oxfordianum : ‘ - oo an 

E. sp. ‘ cn) : Tae 
Psaligonyaulax apaleta a ume oe a. Pirie E Se 
Hexagonifera jurassica 6 5 1 (es eres a e 4 eg 
Parvocavatus tuberosus I 22 1 5 rae 3 s 4 
Scriniodinium bicuncatum 4 ain eee 1 

S. crystallinum i 1 : clas a 5 17 
5. dictyotum subsp. papillatum ef PG io tte 1 

5. dictyotum subsp, pyrum c ol ms \ oo gee 

S. cf, galeatum 3 Tee a 6 2) 6 : 
5. playfordi ieee week oe oo yea es 6 
‘etrelytron parum < mee bY ia = 6 1 a 
N. atogastum cae ae c 3 

Baltisphacridium inusitatum ee ty 
Micrhystridium fragile Ae 159 (ithe old . 
M. inconspicuum. Suen? OS eae orp Em 12 
M. recurvatum Pry eter oo aces 2 17 = «8 5 re 
M. sydus ~ & 5 «© f © 2» » oe 1 eae Be SoGmes 
Solisphaeridium brevispinosum. Hote ig Ss, a, eo ; mc en dr on MS Side er ce Ae rs 
S. stimuliferum ip 4 OY 5) 2 | Es 
Organism A ste Soaeee 2 a ie ce Se 
Veryhachium hyalodermum Re a te welts 1 bp atuhe Mec E 

Staplinium cistum ao Var wis, eet : ids hie Va 103 re 
Pterospermopais australionsix Poh ae ed eee? Mos moo dO Om Ce 
P, harti tie teat p : ee he) Ps bo © 
P. helios eee Ces ae é j wor oo 1S ce OU Gee He 
‘Total number of determined microplankton 207 87 56 110 82 k Pe REY ge ek I gg 
Undetermined microfossils Ren ee ar 188 48 van a Hy s a Fe 87 42 ss 164) BOF GS, 7) 4a 
Foraminiferal shell linings Sonts® 3| a0) ar Re aa Ac eee ec oe oe 
Pollen & Spores daexG) es eateiaMMeeaMeoM 37) 20 54) 65) 224) ms 77) 38 Go 8 st? 9 17 13 
Wood fragments . 38 u 2 5 


Peat 
a 
w 


10 


pow 


5 
Perey 


wo 


ra: 


74 


w 
on 
Se 


a 
Ss 
oe 


B | CC 453 
au 


ToraL 322 235 141 329 146 204 114 31x g28 163 79 308 196 — = — 378 334 168 I0q 222 10 17 13 


nes TABLE 6 


‘Tho distribution of Kimmoridgian microplankton comparing with their Previously known stratigraphic range 


Kimmoridgion 
Previously known stratigraphic range 


Zone 


Scitulas Zone 
Hudlestoni Zone 
Pectinatus Zone 
Rotunda Zone 

Pallasioides Zone 


Eudoxus Zone 
Mutabilis Zone 
Aut 


Baylei Zone 


[s 


Lower Cretaceous (Berriasian-Valanginian) 


Portlandian (Tithonian, Volgian) 


Scotland 
France 
England 

| England 
France 
England 
France 
England 
Fran 
England 
England 
England 

England 
Kimmeridgian 


* | France 


% | Oxfordian 


* 
* 
* 
x 
* 
x 
* 
* 
* 
x 
* 


Chytroelsphaeridia chytroeides Sain 


mantelli bs = a c ‘ ‘ . x 
Ki Sue fn ne Tes) Ved mcr BRry 


pocoe 
jromes warlinghamensis 


Tenvia capitata x 
T, echinat x 
x 
x 


» %) Pre-Callovian 


+ > #| Callovian 


KKH 

eK 

eR KH 
* 

Birt 

KKM 
# 
x 


* 
* 
x 
xe 
ne 
» 
* 
ne 
x* 
* 
x 
Pre 
* 
“ 


T. hystrix 

T. pilosa 

T. »p. ‘ : SuaeAL ze 

Acanthaulax venusta ied ek: eet x Seas tps : oie ems 

Cryptarchaeodinium calcaratom x ae - ee ed aS 

C ef, calearatum ‘ x ‘ ‘ . . ’ . . ’ x 

. sp. (Gitmez, 1970) : i - ets 

Gonyaulacysta aculeata x 

angulosa x 
x 
x 


tal 


cauda 

eladophora 
ehrenbergii 
eisenacki x Aes “A. cane x x 
ef. eisenacki x x : 3 
cf. giuseppel x x | a eee fie f x 


wR KK Re 
“ 


* 


x 
* 
Pe 
* 


x 
x 

G. ef helicoidea x 
hyaloderma x 
x 

x 

x 


* 

* 

* 
wu KE 
HHH: 
nA 


jurneaica x x 
Jorassica var. longicornis x x 
longicornis 

ef, mamillifera 

nuciformis x x 


. 2 
perforans ; ; «| foes 2p & : 
serrata Meter oS a . ee Pee ; : me SS Bs 


* 
Ae 


systremmatos 


Leptodiniam aceras Pos ac eee 
1 amatillis ee 


* 
* 
4 
x 
a 


* 
Ee oo 


L cf, subtile x Sy x i : 5 6 x : x 
Lap. Se Soe aera x C c 
Occixueysta balios op eS 5 oS : ae aise 
©. monoheuriakos ‘i Re 0 os bac 3 a 2 
©. sp. (Gitmez, 1970) x 
Belodinium dysculam yore. ea 
Dictyopyxis areolata 5 ots ft 
D. cf. reticulata Er 
Mistiophora ¢f. ornata x x) 55 
‘Melourogonyaulax dicryptos 5° oe (a) rs 
M. pila a og arte = 
M. staffinensis Fats ty ot? SEY cy OE x x Peareete eo) 0o 
M. sp. (Gitmez, 1970) Mops Jel ye a or: mes) et | 
M. sp. herein Se Geol we 3 - 8 = ob o 
Apteodinium granulatum me 
A. cf maculatum eee: ae 
Pareodinia ceratophora 
‘Trichodinium sp. x Sate dl An Met 5 st Wd | 
Imbatodinium antennatum 3 5 ae sae A : 3 5 tee <0 ay 
1. cf. villosum Se ee Te ORNS. Ses ‘ ae ry por et nt lds oe, Se Xe cree 
jannoceratopais pellucida x Sy 4a ae : i omc - 


PI 


x 
* 
+h 
Pio 
Kanne 
* 
* 
x 
“” 


x 


* 

* 
x 
x 
” 


* 

* 

nH 

nom 

* 

* 

eet 

* 

» 

” 

xo x* 

* 

¥ 

KHnK 
x 
nn 


* 
* 
* 
» 
x 
* 
» 
Py 
P) 
* 


* 
x 


gmontodinium polyplacophorum Sa mee ~ 8 oo 
Proximate cyst sp. indet - ; 2 2 - g . 5 ‘ : 5 Fe SS 
Heslertonia pellucida tA x 5 2. ¢ 
Epiplosphaera reticulospinosa 
Adnatosphaeridium pauelspinum 
Cleistosphaeridium ehrenbergi 
©. polyacanthum 
© polytrichum 
© tribuliferam 
© 5p: (Gime; 1079) 


* 
* 


+ Wie x 
- Ke KW 


x 
x 


KKn nH 
* 


herein 

Tipurichosphaeriafom petilamn 

Oligospbacridium poleherrimom 

Polystephanephorus sarjeantil 

Prolixosphacridium cf, deirense 

P. granulosum 

¥, parvispinum 

‘Systematophora areolata 

5S. orbifera 

S. ovata 

Taeniophora junctispina x 

Stophanelytron redcliffense Aus ear 
x 


x 
x 
x 
bie 
x 
Awe: 


a“ 
Cale Wadia ite ee 


KR RHR KKK: 
-» 


* 
RK 

ne 
KR RK 


wo RK 
Ko KK 
* * 
* 
a Me 
* 
* 
» 
card 
wenn 
* 


5. cf, redeliffense 

S. cf, searburghense 
Endoscrinium ef, campanula 
E, galeritum 

E. luridum 

K. pear 


* 
ca 

"K RAKAAKA RA 
yw 
we 


1 OLA eases 
* 


PAI cay res ‘apalota 
iW ap, (Gitmex, 1970) 
nifera juramica 

RATES eben 
Muderongia simplex 
Sesoel faa nium blewneatun 

er 

i. reas subsp. dictyotum: 
S, dictyotum subsp, ete 
a dictyotum subsp. 

5, dictyotum 


AM: K- 


Br sc 
ah oe 


PEWISESUSeCs (Wisse 5 2 o> 


HHH KH HH He RHR HK 
Pegaso. 2 


= A ee a 


.- > Ee. SS 


0 ec Ee S68 iae Serene 
reef pu «= 


RR RH RK RR 
ooo gee Oe 


+ ae crn 


Biebloa 


cont 1 00 EO 2505 a 


PERIYEEM =) le a = RRS i 


Ke MRA KH 


ooh i ee 


haltlophine rin 


FROM ENGLAND, SCOTLAND AND FRANCE 251 


The assemblages are dominated by proximate cysts, of which 68 species have 
been described. Gonyaulacysta is the dominant genus, represented by 29 species and 
some 800 specimens. The most abundant species is G. juvassica (301 specimens) ; 
this is, however, confined to the Lower Kimmeridgian, predominating in the Baylei 
and Cymodoce Zones and occurring only sparsely in the higher zones of the Lower 
Kimmeridgian. It has already been shown to be present in the Lower and Middle 
Callovian and abundant in the Lower Callovian and Oxfordian: its frequency makes 
it a useful stratigraphic index for these two stages and part-stage. G. nuciformis, 
represented by 184 specimens, ranges throughout the Kimmeridgian and has been 
previously recorded from Upper Callovian and Oxfordian: its presence or absence in 
the Portlandian remains to be elucidated. Three other species, G. longicornis, 
G. granulata and G. granuligera, are each represented by 50-55 specimens; G. granulata 
occurs in the uppermost Oxfordian also, the remaining two species being only 
recorded from the Kimmeridgian. The two latter species are most abundant in the 
Lower Kimmeridgian, though ranging throughout the stage. G. longicornis has a 
more uneven distribution: it is infrequent in the Lower Kimmeridgian, attains 
maximum frequency in the Middle, and was encountered only in the topmost 
(Pallasioides) zone of the Upper Kimmeridgian. G. perforans occurs in the Middle 
and Upper Kimmeridgian in sufficient numbers to serve as a useful index for those 
levels: other species with restricted ranges are numerically less frequent. Four 
other tabulate genera with precingular archaeopyles, Leptodinium, Acanthaulax, 
Cryptarcheodinium and Occisucysta, are also well represented. 

Proximate cysts with apical archaeopyles (genera Tenua, Chytroeisphaeridia, 
Fromea, Egmontodinium, Dictyopyxis, Meiourogonyaulax) are much less important, 
Meiourogonyaulax ranges throughout the Kimmeridgian: the high-crested species 
M. staffinensis is especially conspicuous and a good index fossil. Dictyopyxis was 
not encountered higher than the Lower Kimmeridgian: the other genera appear less 
useful as stratigraphic indices. Two genera of proximate cysts with intercalary 
archaeopyles, Pareodinia and Imbatodinium, are present: the former is long-ranging, 
but the latter (known to date only from the Kimmeridgian) is potentially important. 
Proximochorate cysts were poorly represented by only two genera: the absence of 
Spiniferites is noteworthy and suggests that prior records from the Oxford and 
Kimmeridge Clays were a product of contamination. 

Chorate and cavate cysts were present in comparable numbers (19 and 21 species 
Tespectively). Chorate cysts with complex process groupings (Systematophora, 
Polystephanephorus, Epiplosphaera and Taeniophora) are characteristic, the two 
latter genera being encountered only in the Lower Kimmeridgian. Stephanelytron, 
hitherto known only from the Oxfordian, ranges only as high as the Cymodoce Zone 
and appears an important index. The long-ranging genus Prolixosphaeridium may 
Tepay fuller study, since the circumscription of the species erected to date appears 
most unsatisfactory. Cleistosphaeridium is abundant throughout: in contrast, the 
two species with tubulai spines both had only a sparse representation. 

Of the cavate cysts present, Endoscrinium and Scriniodinium (both abundant 
in the Oxfordian) dwindle in importance markedly after the Lower Kimmeridgian. 
Netrelytron, Psaligonyaulax and Hexagonifera range throughout the stage, the former 

F 


252 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


consistently in low numbers: Muderongia and Sirvmiodinium, characteristically Lower 
Cretaceous, enter only in the uppermost zones. 

Acritarchs are only a minor constituent of these assemblages and consistently 
occur only in low numbers. Acanthomorphs are the most numerous acritarchs, 
especially the various species of Micrhystridium and Solispheridium stimuliferum: 
pteromorphs, prismatomorphs, netromorphs and polygonomorphs are also infre- 
quently present. 

The stress of this study was placed on the lower zones of the Kimmeridgian and 
the horizons of the Middle and Upper Kimmeridgian require further study before a 
full stratigraphical picture can be painted. However, it is clear that there are three 
distinct phases: in the first phase (Baylei, Cymodoce and, in some measure, Mutabilis) 
the assemblages retain a characteristically Oxfordian allure: in the second, they have 
a distinct identity which may be termed characteristically Kimmeridgian: and in the 
third (Rotunda and Pallasioides) the assemblages begin to acquire Lower Cretaceous 
characters though still retaining a dominantly Upper Jurassic allure. 

Thirty-eight species were observed to range throughout the Kimmeridgian: 26 
further species were recorded both from the Lower and Upper and must be assumed 
to range through the Middle Kimmeridgian. Thirty seven species were recorded 
only from the Lower Kimmeridgian, seven others in the Lower and Middle Kim- 
meridgian. Five species occurred only in the Middle and Upper, four only in the 
Middle, nine only in the Upper Kimmeridgian. The imbalance in the number of 
characteristic species certainly reflects the imbalance in study. It is already possible 
to distinguish from the study of an assemblage, whether it is from the Lower, Middle 
or Upper Kimmeridgian: it should be possible, in the future, to determine that the 
sample came from a particular ammonite zone or from one of two adjacent zones. 

Whether it will be possible in the future to distinguish, as well as to correlate 
between the assemblages from France, England and Scotland is less clear: the present 
authors consider that the similarities between the English and Scottish assemblages 
and those from northern France are so great as to make it virtually certain that these 
areas were all part of one plankton province in one water body (which agrees with 
what is known of Jurassic palaeogeography). Fuller information is needed on the 
assemblages from central France (Crussol and the Jura) before any meaningful 
commentary can be made, but it should be noted that surprisingly few of the species 
described from the latter locality by Deflandre (1939, 1941) were encountered in this 
study. Of 19 species described by Klement (1960) from the Kimmeridgian of South 
Germany, only seven were identified in the assemblages studied. It thus appears 
probable that these assemblages were drawn from a different plankton province, and 
hence a different water body. Future studies of these microfossils promise to aid in 
elucidating the pattern of water circulation in the Jurassic. 


VI. ACKNOWLEDGEMENTS 


The bulk of the work by the first author was carried out, under supervision by 
the second author, during her tenure of a research studentship awarded by the 
Scientific and Technical Research Council of Turkey. Samples were collected under 


FROM ENGLAND, SCOTLAND AND FRANCE 253 


guidance from, or provided by, a number of geologists listed in the “‘Introduction’”’, 
to all of whom the authors would like to express their thanks. Both authors, during 
their work at the University of Nottingham, have received considerable help from 
Mr. R. D. Hendry and his staff, especially Mr. John Eyett and Mr. K. J. Cass in 
photography ; they would also like to thank Professor the Lord Energlyn of Caerphilly 
for his support and encouragement. Mr. L. A. Riley is thanked for making some 
corrections to the stratigraphical conclusions. 


VII. REFERENCES 


Acer, D. V. & Evamy, B.D. 1963. The Geology of the Southern French Jura. Proc. Geol. 
Ass., London, 74, 3 : 325-356, figs 1-6. 

Acer, D. V. & Ramsay, J. G. 1963. Summer Field Meeting in the French Jura and Alps, 
July 1963. Proc. Geol. Ass., London, 74, 4 : 483-515, figs 1-4. 

Acer, D. V. & SmirH, W. E. 1965. The Coast of South Devon and Dorset between Brans- 
combe and Burton Bradstock. Geol. Ass. Guide, London, no. 23 : 1-21, figs 1-5. 

Acer, D. V. & WaALLAcE, P. 1966a. The Environmental History of the Boulonnais. Pyroc. 

Geol. Ass., London, 77, 4 : 385-418, figs 1-9. 

1966b. Easter Field Meeting in the Boulonnais, France. Proc. Geol. Ass., London, 

77, 4 : 419-436, pls. 19-21, figs 1-4. 

ALBERTI, G. 1961. Zur Kenntnis mesozoischer und alttertidrer Dinoflagellaten und 
Hystrichosphaerideen von Nord- und Mitteldeutschland sowie einigen anderen europdischen 
Gebieten. Palaeontographica, Stuttgart Abt.A, 116 : 1-58, pls. 1-12, table 1. 

AnpeErson, F. W. & DuNnHam, K. C. 1966. The Geology of Northern Skye. Mem. Geol. 
Surv. Scotland, Edinburgh, 216 : 1-216, pls. 1-4, figs 1-23. 

ARKELL, W. J. 1933. The Jurassic System in Great Britain. University Press, Oxford. 

681 pp., 47 pls., 97 figs. 

1930. Geology of Oxfordshire, in L. F. Salzman (ed.). Victoria History of the County of 

Oxford, vol. 1, University Press, Oxford. (1-26, 1 map.) 

1941. Dorset Geology, 1930-1940. Pyoc. Dorset Nat. Hist. Archaeol. Soc., Dorchester, 


61, 117. 

1946. Standard of the European Jurassic. Bull. Geol. Soc. Am., New York, 57 : 1-34, 
tables 1-4. 

1951. Dorset Geology, 1940-1950. Proc. Dorset Nat. Hist. Avchaeol. Soc., Dorchester, 
72 : 176-194. 

1956. Jurassic Geology of the World. Oliver & Boyd, Edinburgh. 1—806, 102 figs, 28 
tabs. 


Battes, N. 1963. Dinoflagellate si Hystrichosphaeride cretacice din Platforma moesica. 
Petrol si Gaze, Bucuresti, 12 : 581-597, pls. 1-8. 

1965. Observatii asupra microflorei cretacice inferioare din zona R. Bicaz. Petrol si 
Gaze, Bucuresti, 16, 3-17, pls. 1-4, fig. 1. 

1967a. The microflora of the Albian “‘Green Sands” in the Moesic Platform (Rumania). 
Rev. Palaeobot. Palynol., Amsterdam, 5, 183-197, pls. 1-4, figs 1-4. 

1967b. Albian microplankton from the Moesic Platform, Rumania. Mucvopaleontology, 
New York, 131 : 1, 327-336. 

1969. Discontinuitati in repartita microflorei cretacice din Platforma moesica. Petrol 
st Gaze, Bucuresti, 20, 332-338, figs 1-5. 


254 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


Beju, D. 1969. Jurassic Microplankton from the Carpathian Foreland of Romania. A pre- 
print for the “Colloquium on the Mediterranean Jurassic, 1969”. I-12, pls. 1-8, figs 1-7. 

Brito, I.M. 1967. Osacritarcha. Notes prelim. Estud. Serv. geol. min. Brasil No. 138, 1-21, 
pls I-II. 

Brown, R.W. 1956. Composition of Scientific Words. Reese Press for the Author, Baltimore, 
Md., 1-882. 

CLARKE, R. F. A. & VERDIER, J. P. 1967. An investigation of Microplankton Assemblages 
from the Chalk of the Isle of Wight, England. Verh. K. ned. Akad. Wet., Amsterdam, 
24, 3 : 1-96, pls. 1-17, figs 1-32. 

Cookson, I. C. & Etsenack, A. 1958. Microplankton from Australian and New Guinea 

Upper Mesozoic sediments. Pvoc. R. Soc. Vict. Melbourne, 70, 1 : 19-79, pls. 1-12, t-figs 

I-20. 

1960a. Upper Mesozoic microplankton from Australia and New Guinea. Palaeontology, 
London, 2, 2 : 243-261, pls. 37-39, t-figs 1-4. 
1960b. Microplankton from Australian Cretaceous sediments. Mucropaleontology, New 

York, 6, 1 : 1-18, pls. 1-3, t-figs 1-6. 

1961. Upper Cretaceous microplankton from the Belfast no. 4 bore, South-Western 

Australia. Proc. R. Soc. Vict., Melbourne, 74, 1 : 69-76, pls. 11-12, t-figs I. 

1962. Additional microplankton from Australian Cretaceous sediments. Muicropaleon- 

tology, New York, 8, 4 : 485-507, pls. 1-5, t-figs 1-2. 

Cooxson, I. C. & HucHEs, N. F. 1964. Microplankton from the Cambridge Greensand (mid- 
Cretaceous). Palaeontology, London 7, 1 : 37-59, pls. 5-11. 

Cope, J. C. W. 1967. The Palaeontology and stratigraphy of the lower part of the Upper 
Kimmeridge Clay of Dorset. Bull. Br. Mus. nat. Hist. (Geol.), London, 15, 1 : 1-79, 
pls. 1-33, figs 1-22. 

Craic, G. Y. 1965. The Geology of Scotland. Oliver & Boyd, Edinburgh, 1-556, fig 16. 

Davey, R. J. 1969. Non-Calcareous Microplankton from the Cenomanian of England, 
Northern France and North America, pt. 1. Bull, By. Mus. nat. Hist. (Geol.), London, 
17, 3 : 103-180, pls. 1-11, figs 1-16. 

Davey, R. J., Downie, C., SARJEANT, W. A.S. & Wittiams,G.L. 1966. Studies on Mesozoic 
and Cainozoic Dinoflagellate cysts. Bull. By. Mus. nat. Hist. (Geol.), London. Suppl. 
3 : 1-248, pls. 1-26, figs 1-64. 

; ; ; 1969. Appendix to “Studies on Mesozoic and Cainozoic Dinoflagellate 
Cysts’. Bull. Br. Mus. nat. Hist. (Geol.), London. Appendix to suppl. 3, 1-24. 


Davey, R. J. & Wittiams, G. L. 1966. See Davey, R. J. and others. 


DEFLANDRE, G. 1938. Microplancton des mers jurassiques conservé dans les marnes de 
Villers-sur-Mer (Calvados). Tvav. Stn. zool. Wimereux., Paris, 13 : 147-200, pls. 5-11, 
t-figs I-10. 
1939a. L’étude microscopique des silex. Sciences Naturelles, 1 : 259-264, t-figs 1-24. 
1939b. Sur les dinoflagellés des schistes bitumineux d’Orbagnoux (Jura). Bull. Soc. 
Fy. Microsc., Paris, 8, 4 : 141-145, pl. 6. 
1941a. La vie créatice des voches. Le véle bdtisseur des étves microscopique et la genése des 
houilles et des pétyéles. Presses Universitaires de France, Paris, Collection ““Que Sais-Je”’. 
1-128, t-figs 1-25. 
1941b. Le microplancton Kiméridgien d’Orbagnoux et l’origine des huiles sulfurées 
naturelles. Mém. Acad. Sci., Paris, no. 65, 1-32, pls. 1-7, t-figs 1-7. 
1966a. Addendum 4 mon Mémoire: Microfossiles des Silex Crétacés. Arch. orig. Centre 
document. C.N.R.S., Paris no. 419, I-9, pl. 1. 
1966b. Etude micropaléontologique des Silex du site de Pincevent. Gallia préhistoive, 
Gy, Tao), A 8 Shei, Jol, ©. 
DEFLANDRE, G. & Cookson, I. C. 1954. Sur le microplancton fossile conservé dans diverses 
roches sédimentaires australasiennes s’étageant de Crétacé inférieur au Miocene supérieur. 
C. rv. hebd. Séanc. Acad. Sci., Paris, 239, 19 : 1235-8, t-figs I-17. 


FROM ENGLAND, SCOTLAND AND FRANCE 255 


DEFLANDRE, G. & Cookson, I. C. 1955. Fossil microplankton from Australia late Mesozoic 
and Tertiary sediments. Aust. J. mar. Freshwat. Res., Melbourne, 6 : 242-313, pls. 1-9, 
t-figs I-59. 

DEFLANDRE, G. & DEFLANDRE, M. 1962. Fichier micropaléontologique générale. Dino- 
flagellés III. Arch. orig. Centre document C.N.R.S. Paris, 383, fiches 1751-1947. 

—, 1966a. Fichier micropaléontologique générale. Dinoflagellés V. Arch. orig. 
Centre docum. C.N.R.S., Paris, fiches 2876-3175. 

—, 1966b. Fichier micropaléontologique générale. Dinoflagellés VI. Avch. orig. 
Centre docum. C.N.R.S., Paris, fiches 3237-3307. 

DEFLANDRE, G. & SaRJEANT, W. A. S. 1969. Nouvel examen de quelques holotypes de 
Dinoflagellés fossiles et d’Acritarches. Arch. orig. Centre docum. C.N.R.S. No. 466, I-10, 
plea: 

DeEtcourt, A. & SPRUMONT, G. 1957. Quelques microfossiles du Wéaldien de Féron-Glageon. 
Bull. Soc. géol. belg., 6, 1 : 57-68, pls. 1-3. 

DopveEKova, L. 1967. Les dinoflagellés et acritarches de |’Oxfordien-Kimméridgien de la 

Bulgarie du Nord-est. Ann. Univ. Sofia, 60 : 1-29, pls. 1-3, figs 1-2. 

1969. Dinoflagellés et Acritarches du Tithonique aux environs de Pleven, Bulgarie 
Centrale du Nord. Bull. geol. Inst. Sofia, 18 : 13-24, pl. 1-5, text-figs A—H, table 1. 
DownleE, C. 1957. Microplankton from the Kimeridge Clay. Q.J.G.S. London, 112 : 413- 

434, pl. 20, t-figs 1-6. 

DownlE, C. & SARJEANT, W. A.S. 1964. Bibliography and Index of fossil dinoflagellates and 
acritarchs. Mem. Geol. Soc. Am., Washington, no. 94 : 1-180. 

Etsenack, A. 1958. Mikroplankton aus dem norddeutschen Apt nebst einigen Bemerkungen 
iiber fossile Dinoflagellaten. Neues Jb. Geol. Paléont. Abh., Stuttgart, 106 : 383-422, pls. 

21-27. 

1961. Einige Erérterungen iiber fossile Dinoflagellaten nebst Ubersicht iiber die zur 
Zeit bekannten Gattungen. Neues Jb. Geol. Paléont. Abh., 112, no. 3 : 281-324, pls. 33-37, 
t-figs I-7. 

1964. Katalog der fossilen Dinoflagellaten, Hystrichosphaven und verwandten Mikrofossilien. 
Schweizerbart, Stuttgart. 1-895, 9 pls. 

EIsENAcK, A. & Cookson, I. C. 1960. Microplankton from Australian Lower Cretaceous 
sediments. Pyvoc. R. Soc. Vict., Melbourne, 72, 1 : 1-11, pls. 1-3. 

GitMEz, G. U. 1970. Dimnoflagellate Cysts and Acritarchs from the Basal Kimmeridgian 
(Upper Jurassic) of England, France and Scotland. Bull. By. Mus. nat. Hist. (Geol.). 
18, 7 : 231-331, pl. 1-14, text-figs 1-34. 

Gocut, H. 1964. Planktonische Kleinformen aus dem Lias/Dogger-Grenzbereich Nord-und 

Sitiddeutschlands. Neu. Jb. Geol. Paldont. Abh., Stuttgart, 119; 113-133, pls. 15-17, figs 

I-57. 

1970. Dinoflagellaten-Zysten aus den Bathonium des Erdélfeldes Aldorf (N W— 
Deutschland). Palaeontographica, Stuttgart, Abt. B, 129 : 125-165, pls. 26-35. 

Gé6rKa, H. 1965. Les microfossiles du Jurassique Supérieure de Magnuszew (Pologne). 
Acta. palaeont. pol., Warszawa, 10 : 291-334, pls. I-5. 

KarveE-Corvinus, G. 1966. Buiostratigraphie des Oxfordium und untersten Kimmeridgium 
am Mont Crussol, Ardéche, im Vergleich mit Siiddeutschland N. Jb. Geol. Paliéont Abh. 
Stuttgart 2 : 101-141, pls. 22-26. 

KLEMENT, K. W. 1960. Dinoflagellaten und Hystrichosphaerideen aus dem Unteren und 
Mittleren Malm Siidwestdeutschlands. Palaeontographica, Stuttgart, Abt.A, 114 : 1-104, 
pls. 1-7, t-figs 1-37. 

Manvum, S. & Cooxson, I. C. 1964. Cretaceous microplankton in a sample from Graham 
Island, Arctic Canada, collected during the second ‘“‘Fram-” Expedition (1898-1902), 
with notes on microplankton from the Hassel Formation, Ellef Ringnes Island. Shr. 
Norske Vidensk-Akad. mat. Nat. Kl. (N.S.)., Oslo, 17 : 1-36, pls. 1-7. 

Mititioup, M.E. 1967. Palynological study of the type localities at Valangin and Hauterive. 
Rev. Palaeobot. Palynol., Amsterdam, 5 : 155-167, pls. 1-2, fig. I. 


256 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS 


MorcEenrotH, P. 1966. Mikrofossilien und Konkretionen des Nordwesteuropdischen 
Untereozans. Palaeontogvaphica, Stuttgart, Abt. B, 119 : 1-53, pls. 1-11, table 1. 

Norris, G. & SARJEANT, W. A.S. 1965. A descriptive index of genera of fossil Dinophyceae 
and Acritarcha. Bull. Geol. Surv. N.Z., Wellington, no. 40 : 1-72. 

Roman, F. 1936. Geology of the Rhone Valley (Lyons-Crussol). Proc. Geol. Ass., London, 
47 : 153-182, figs 40-48. 

SARJEANT, W. A. S. 1960. New hystrichospheres from the Upper Jurassic of Dorset. Geol. 
Mag., London, 97, 2 : 137-144, pl. 6, t-figs 1-4. 

— 1961a. Microplankton from the Kellaways Rock and Oxford Clay of Yorkshire. 
Palaeontology, London, 4, i : 90-118, pls. 13-15, t-figs I-15. 

1961b. Systematophora Klement and Polystephanosphaera Sarjeant. J. Paleont., Tulsa, 
Oklahoma, 35, 5 : 1095-1096. 

1962a. Upper Jurassic microplankton from Dorset, England. Micropaleontology, 
New York, 8, 2 : 255-268, pls. 1-2, t-figs 1-8, tables 1-4. 

196zb. Microplankton from the Ampthill Clay of Melton, South Yorkshire. Palaeon- 
tology, London 5, 3 : 478-497, pls. 69-70, t-figs 1-13, tables 1-3. 

1963. Fossil dinoflagellates from Upper Triassic sediments. Nature, Lond. 199, no. 
4891 : 353-354, t-figs 1-3. 

1964. The stratigraphic application of fossil microplankton in the Jurassic. In P. L. 
Maubeuge (ed.) Colloque du Jurassique, Luxembourg 1962, Volume des comptes-vendus et 
mémotres, Inst. Grand-Ducal, Sect. Sci. Natur., Luxembourg, 441-448, tables 1-4. 

1965. Microplankton from the Callovian of Normandy. Revue Micropaléont. Paris, 
8, 3 : 175-184, pl. I, fig. 1. 

1966. (See Davey, R. J., and others, 1966.) 

1967a. The genus Palaeoperidinium Deflandre 1934 (Dinophyceae). Gvrana palynol., 
Uppsala, 7, I : 241-258, figs 1-6. 

1967b. The stratigraphical distribution of fossil Dinoflagellates. Rev. Palaeobot. 

Palynol., Amsterdam, 1 : 323-343, tables, 1-1. 2 

— 1967c. Observations on the Acritarch genus Micrhystridium (Defl.). Revue Micro- 
paléont., Paris 9, 4 : 201-208, pl. 1, fig. 1. 

1968. Microplankton from the Upper Callovian and Lower Oxfordian of Normandy. 
Revue Micropaléont., Paris, 10, 4 : 221-242, pls. 1-3, figs 1-5, tables 1-2. 

1969. (See Davey, R. J. and others, 1969.) 

SARJEANT, W. A. S. & DownlE, C. 1966. The classification of Dinoflagellate Cysts above 
generic level. Gvana Palynol, Uppsala, 6, 3 : 503-527. 

Scuurz, E. & Mar, D.H. 1966. Erlauterungen zur Tabelle der stratigraphischen Verbreitung 
des Phytoplanktons im Lias und Dogger. In H. Doring et. al. (eds.): Erlauterungen zu 
den sporenstratigraphischen Tabellen vom Zechstein bis zum Oligozan, Zentr. Geol. Inst. 
Abh., Berlin, H8 : 35-45, table 1. 

STAPLIN, F. L., JANsonius, J. & Pocock, S. A. J. 1965. Evaluation of some acritarchous 
hystrichosphere genera. Neues Jb. Geol. Paldont Abh., Stuttgart, 123 : 167-201, pls. 18-20. 

VALENSI, L. 1953. Microfossiles des silex du Jurassique moyen. Remarques pétrographiques. 

Mem. Soc. geol. Fr., Paris, 68 : 1-100, pls. 1-16, t-fig. 1-7. 

1955. Etude micropaléontologique des silex du Magdalénien de Saint-Amand (Cher). 

Bull. Soc. préhist. Fr. Paris, 52, 9-10 : 584-596, pls. 1-5. 

VOZZHENNIKOVA, T. F. 1967a. Intvoduction to the study of fossilized peridinid algae. National 
Lending Library for Science Technology, Boston Spa, Yorks, England. (English trans- 
lation by K. Syers, edited by W. A. S. Sarjeant). 233+ xiii, figs 1-51, tables 1—10. 

—— 1967b. Iskopayemiye peridinot yurskikh, myeolovikh, palaeogenovikh otlozhenty S.S.S.R., 
Moscow, Nauka, 1-347, pls. 1-120, 14 figs. 12 tables. 

Walt, D. & Downtz, C. 1963. Permian hystrichospheres from Britain. Palaeontology, 
London 5, 4 : 770-784, pls. 112-114, t-figs 1-4. 

Waterston, C. D. 1951. The stratigraphy and palaeontology of the Jurassic Rocks of 
Eathie (Cromarty). Tvans. R. Soc. Edin., Edinburgh, 62 : 33-52, pls. 1-2, figs 1-4. 


FROM ENGLAND, SCOTLAND AND FRANCE 257 


WETZEL, W. 1966. Characteristik des marinen Planktons und Pseudoplanktons der Amaltheen- 
Schichten Deutschlands und Lothringens. Neues Jb. Geol. Paldéont. Abh., Stuttgart, 124, 
3 : 313-326, pls. 30-31. 

Wittiiams, D. B. & SaryjEANT, W. A. S. 1967. Organic-walled Microfossils as depth and 
shoreline indicators. Mar. Geol., Amsterdam, 5 : 389-412, figs 1-16. 

Wittiams, G. L. & DownlE, C. 1966. See Davey, R. J. et al. 


Mrs G. U. GitmeEz, Ph.D., 
Dept. of Geology, 
HACETTEPE UNIVERSITY, 
ANKARA, 

TURKEY 


W. A. S. SaRJEANT, B.Sc., Ph.D., F.G.S., F.L.S., 
Dept. of Geology, 

UNIVERSITY OF SASKATCHEWAN, 

SASKATOON, 

CANADA 


Fic. 1. 
FIG. 9. 
Fie. 2 
Fic. 3 
Fic. 4 
Fic. 5 
Fig. 6 
Fie. 8 
1ges / 
FIG. 10 
Fic. 11 
FIG. 12 


PLATES: 


Tenua echinata sp. nov. 
General appearance and archaeopyle formation of the holotype, 
V.52790(I) x716. 
Paratype, I.G.S. slide PK 119 450. 
Chytroeisphaeridia chytroeides Sarjeant 
IEG Sa slid pe ke Tro2 Aw Gr53o: 
Chytroeisphaeridia mantelli sp. nov. 
Holotype, showing archaeopyle with attached operculum. 
I.G.S. shde PK 116 560. 
Paratype A, I.G.S. slide PK 114 500. 
Chytroeisphaeridia pococki Sarjeant 
BM(NH) slide V.53961(3) 1600. 

Fromea warlinghamensis sp. nov. 
Holotype (b) I.G.S. slide PK 115 720. 
Paratype BM(NH) slide V.56340 (1) x5IOo. 

Tenua sp. 
BM(NH) slide V.53619 (1) 690. 
Same specimen taken by phase contrast. 690. 
Tenua capitata (Cookson & Eisenack) 
Specimen with attached operculum. 
BM(NH) slide V.56341 x8 40. 
Same specimen by phase contrast. 8 40. 


Bull. By. Mus. nat. Hist. (Geol.) 21, 5 


IPIEAN IIS, at 


ey 


aor 


eon F 
7 


ne 


coo™I 


IPIL IN IID, 2 


Gonyaulacysta cauda sp. nov. 
Ventral view of the holotype. 
BM(NH) slide V.53965 (2) 614. 
Dorsal view of the holotype. x 6r4. 


Ventral view of the paratype. BM(NH) slide V.56343 (1) 716. 
Dorsal view of the paratype, by transparency. 716. 
Cryptarchaeodinium cf. calcaratum 


Dorsal view. BM(NH) slide V.56342 xc. 1 


,000. 


Gonyaulacysta longicornis (Downie) 


A specimen from the Middle Kimmeridgian. 


1.G.S. slide PK 120. 


Gonyaulacysta cladophora (Deflandre) 
I.G.S. slide PK r10. 464. Sample WB7 (Eudoxus Zone). 


Same specimen by phase contrast. x 464. 


x 496. 


IPIL JANIS, 2 


Bull. By. Mus. nat. Hist. (Geol.) 21, 5 


Fic. 
Fic. 


Fila. 
Fig. 


Fic. 


Fic. 
Fie. 


Fic. 


FiG. 


iS) 


Ww 


PLATE 3 


Gonyaulacysta globata sp. nov. 
Holotype, I.G.S. slide PK 122. 625. 
Paratype BM(NH) slide V.56345. x 6r4. 
Gonyaulacysta cf. guiseppei Morgenroth 
BM(NH) slide V.56344. Ventral view. 600. 
Dorsal view of the same specimen, showing the archaeopyle. 600. 
Gonyaulacysta nuciformis (Deflandre) 
Ventral surface of specimen. I.G.S. slide PK 109. 576. 
Gonyaulacysta eisenacki (Deflandre) 
BM(NH) slide V.56375. Showing the ventral tabulation. x 8go. 
Dorsal view of the same specimen. x 8go. 
Leptodinium cf. crassinervum (Deflandre) 
Specimen with detached operculum. BM(NH) slide V.56351 (1) x 384. 
Leptodinium sp. 
BM(NH) slide V.56352. 572. 


Bull. By. Mus. nat. Hist. (Geol.) 21, 5 IP ILE, 3} 


Fic. 


Fic. 


Fic. 


Fia. 


Fig. 


Fic. 


Fic. 


PLATE 4 


Gonyaulacysta longicornis (Downie) 
A specimen from the Upper Kimmeridgian. 
Gonyaulacysta sp. B 
Ventral view of a specimen from the Middle Kimmeridgian. 


I.G.S. slide PK 117. 


x 840. 


Dorsal view of the same specimen. 
Meiourogonyaulax sp. 


BM(NH) slide V.56359 (1). 


x 840. 


BM(NH) slide V.56346 (2). 


The operculum is still attached. 614. 


Meiourogonyaulax pila sp. nov. 
BM(NH) shde V.56358. Holotype. 
Gonyaulacysta perforans (Cookson & Eisenack) 


1.G.S. slide PK 131. 


x 1430. 


x 6901. 


Gonyaulacysta cf. mamillifera 


1.G.S. shde PK 130. 


x 759. 


x 480. 


Bull. Br. Mus. nat. Hist. (Geol.) 21, 5 IPILININIS, A 


Fic. 
Fic. 
Fic. 


TG: 
Fic. 
Eines 


Fic. 
Fic. 


WO NH 


Ore 


on 


DIGAINE ¢ 


Leptodinium aceras (Eisenack) 
Ventral surface. I.G.S. slide PK 108. 640. 
Dorsal surface of the same specimen. 640. 
A specimen from the Lower Kimmeridgian. I.G.S. slide PK 112. 626. 
Leptodinium cf. crassinervum (Deflandre) 
Tabulation on the ventral side. BM(NH) slide V.56346 (1 & 3). 768. 
Dorsal surface of the same specimen; plate 3” is lost in archaeopyle formation 
Dorsal view of another specimen, with operculum still attached. 
BM(NH) slide V.56351 (1). 480. 
Gonyaulacysta systremmatos sp. nov. 
Holotype BM(NH) slide V.53966 (1), showing the ventral surface. 848. 
Dorsal view of the holotype. 848. 


x 768. 


Bull. Br. Mus. nat. Hist. (Geol.) 21, 5 PLATE 5 


Fic. 
Fic. 


Fic. 
Fiac. 


Fic. 
Fia. 


EK 
Fic. 


Fia. 


H 


one 


Oi 


IPL NAD, 


Gonyaulacysta sp. C 
I.G.S. shde PK 118. taken by phase contrast. 656. 


Same specimen, by Nomarski interference contrast. 


Gonyaulacysta sp. F 
Left lateral view. BM(NH) slide V.56348 (1). x 512. 


Right lateral view, as seen by Nomarski interference contrast. 


Gonyaulacysta sp. D 
Ventral view. BM(NH) slide V.56346 (4). 580. 
Dorsal view of the same specimen. 580. 
Gonyaulacysta sp. G 
Ventral view. BM(NH) slide V.56349 (1). 768. 


Dorsal view. 768. 


Gonyaulacysta sp. E 


Ventral view of the specimen. 


I.G.S. slide PK 113. 


x 656. 


x 680. 


x 512. 


6 


PLATE 


Mus. nat. Hist. (Geol.) 21, 5 


Bull. Br. 


On 


. 10. 
. It. 


PLATE 7 


Leptodinium egemenii Gitmez 


Ventral surface of the paratype, BM(NH) slide V.52798 (3), by phase contrast. 
Dorsal view of the paratype: plate 3” lost in archaeopyle formation. 574. 


Meiourogonyaulax pila sp. nov. 
General appearance of the paratype, showing the attached operculum. 
I.GiS. slide PK 121. 544. 
Dictyopyxis cf. reticulata (Valensi) 
Ventral surface of specimen. BM(NH) slide V.56354 (1). 768. 
Dorsal view, showing the median band equivalent to a cingulum. 768. 
Meiourogonyaulax dicryptos sp. nov. 


Holotype, with apical archaeopyle; taken using Nomarski interference contrast. 


BM(NH) slide V.56357 (1). x 704. 

Histiophora cf. ornata 
Specimen with apical archaeopyle. BM(NH) slide V.52964 (1). 768. 
Same specimen, taken by phase contrast. 768. 

Dictyopyxis areolata Cookson & Eisenack 
BM(NH) slide V.53956 (1). Specimen with apical archaeopyle. 614. 
Occisucysta monoheuriskos sp. nov. 

Ventral view of the holotype. BM(NH) slide V.56353 (1). 615. 


Dorsal view of the holotype, showing the two-plate precingular archaeopyle. 


Meiourogonyaulax sp. 
Specimen with attached operculum. I.G.S. slide PK 100. 1200. 


« O15. 


7 


PLATE 


Mus. nat. Hist. (Geol.) 21, 5 


Bull. Br. 


FIGS. I-2. 


Fics. 3-4. 


PPA Ess 


Egmontodinum polyplacophorum gen. et. sp. nov. 
Holotype, BM(NH) slide V.56360 (2b). 1. In ventral view. 2. In dorsal view, 


by transparency. 1215. 
Paratype (a), BM(NH) slide V.56360. 3. In oblique ventral view, by transparency | 


details of posterior not visible. 4. In oblique dorsal view. 1215. 


PIL JAI, 8 


Bull. By. Mus. nat. Hist. (Geol.) 21, 5 


nN 


PLATE 9 


Gonyaulacysta sp. A Gitmez and herein 
BM(NH) slide V.56347 (2). 720. 
Detail of apex by phase contrast, showing the short spines on crests. 1215. 
Egmontodinium polyplacophorum gen. et. sp. nov. 
Paratype (c), showing apical archaeopyle. BM(NH) slide V.56347 (1). 720. 
Meiourogonyaulax staffinensis Gitmez 
BM(NH) slide V.56356. xc. 720. 
Fromea warlinghamensis sp. nov. 
Paratype (a), BM(NH) slide V.56339 (2). 720. 


Detail of surface, showing bulges and polygonal patterning considered to be produced 


by pressure of mineral grains. 215. 


9 


PLATE 


Mus. nat. Hist. (Geol.) 


Bull. Br. 


Fic. 
Fic. 
Fic. 
Fic. 


Fic. 
Fic. 


Fic. 


PLATE to 


Adnatosphaeridium paucispinum (Klement) 


BM(NBH) slide V.56365 (1). 480. 
Same specimen taken by phase contrast. x 480. 


Specimen with apical archaeopyle. BM(NH) slide V.56366 (2). 


phase contrast. 544. 


Dorsal view of the same specimen by phase contrast. 544. 


Leptodinium amabilis (Deflandre) 
Ventral view. BM(NH) slide V.56350 (1). 1200. 


Cleistosphaeridium ehrenbergi (Deflandre) 


BM(NH) slide V.56376 Sample LO353, by phase contrast. 


x 651. 


Ventral view, by 


. Dorsal view of the same specimen, showing the precingular archaeopyle. 1200. 


Bull. Br. Mus. nat. Hist. (Geol.) 21, 5 PLATE ro 


Fic. 


Fic. 
Fic. 


Fic. 
Fic. 
Fic. 
Fia. 


Fic. 
Fic. 


0 


IPILVNANIS, ann 


Imbatodinium cf. villosum Vozzhennikova 
BM(NH) slide V.56362 (1); specimen from the Upper Kimmeridgian of Dorset. 608. 
Imbatodinium antennatum sp. nov. 
Paratype, showing the intercalary archaeopyle. BM(NH) slide V.56361 (1). 768. 
Holotype, showing the intercalary archaeopyle. I.G.S. sude PK 124. 845. 
Proximate cyst sp. indet. 
Specimen with attached operculum. BM(NH) slide V.56363 (1). 513. 
Same specimen, taken by Nomarski interference contrast. 513. 
General view of another specimen; BM(NH) slide V.56364. 451. 
Egmontodinium polyplacophorum gen. et. sp. nov. 
Holotype in ventral view, showing the tabulation. BM(NH) slide V.56360 (2b). 
x 640. 
Dorsal view of the holotype, by transparency. 640. 
Paratype (c), showing apical archaeopyle. BM(NH) slide V.56347 (1). x 1024. 


PIL ANTES, wi 


Mus. nat. Hist. (Geol.) 21, 5 


Bull. Br. 


/ 


Nor 
* 

a 

. 


om 


ines 


FIG. 


nee 


1BKE, AL, 
Fic. 


Fic. 


Fic. 


Fie. 
Fic. 


oe) 


9. 


JIC PNAD IS, 12 


Dictyopysxis cf. reticulata (Valensi) 
In presumed oblique ventral aspect. BM(NH) slide V.56355 (1). 768. 
Same specimen in presumed oblique dorsal aspect showing the apical archaeopyle. 
< 768. 
Chytroeisphaeridia mantelli sp. nov. 
Paratype B, showing the archaeopyle and slits. BM(NH) slide V.56338 (1). 532. 
Apteodinium granulatum Eisenack 
Ventral view of specimen. I.G.S. slide PKi1o2z. 592. 
Dorsal view of the same specimen, showing the precingular archaeopyle. 592. 
Apteodinium cf. maculatum Eisenack & Cookson 
I.G.S. slide PK 105. 464. 
Pterospermopsis australiensis Deflandre & Cookson 
BM(NH) slide V.56353 (2) Sample CS421. x 1000. 
Polystephanephorus sarjeantii Gitmez 
Holotype by phase contrast. BM(NH) slide V.52792 (2), sample OM 131. 580. 
Holotype showing the apical archaeopyle. (Phase contrast). 580. 


y 2 


IPL NA 


Ib 5) 


2 


Mus. nat. Hist. (Geol.) 


Bull. Br. 


Fic. 


Fic. 


Fic. 


Fic. 


Fia. 


Fic. 
Ges 


NOW 


IPL AN IIS 03) 


Gonyaulacysta sp. H 
Oblique ventral view BM(NH) slide V.56339 (1), sample CH231. 720. 
Systematophora orbifera Klement 
Showing apical archaeopyle. BM(NH) slide V.56377, sample OM 418. 
Oligosphaeridium pulcherrimum (Deflandre & Cookson) 
BM(NH) slide V.56368 (1), sample CC 449. 800. 
Scriniodinium sp. 

Ventral view of the specimen I.G.S. slide PK 107. 448. 

Prolixosphaeridium granulosum (Deflandre) 
BM(NH) slide V.52799 (4); from the sample OM 131. 768. 
Specimen with attached operculum. I.G.S. slide PK 103. 573. 


x 720. 


Specimen lacking the operculum. BM(NH) slide V.53960 (3). Sample SC 444. 


x 1024. 


Ih 5) 


2 


Mus. nat. Hist. (Geol.) 


Bull. By. 


Fic. 
Fic. 
Fic. 


Fic. 


Fic. 
Fia. 


Fic. 
Fic. 
Fic. 


Fic. 
Ge 


nN 


10. 
JE 


PLATE 14 


Systematophora ovata sp. nov. 
Paratype. BM(NH) slide V. 56343 (2) 717. 
Holotype, with apical archaeopyle. BM(NH) slide V.53962 (1). 800. 
Same specimen, under phase contrast. x 800. 
Parvocavatus tuberosus Gitmez 
BM(NH) slide V.56353 (3). Sample ES 421. x1075. 
Hexagonifera jurassica sp. nov. 
Holotype, with attached operculum. I.G.S. slide PK 123. 350. 
Paratype with apical archaeopyle. BM(NH) slide V.53621 (1). 8109. 
Stephanelytron redcliffense Sarjeant 
BM(NH) slide V.56366 (1). 8 o. 
Stephanelytron cf. redcliffense Sarjeant 
Specimen with apical archaeopyle. BM(NH) slide V.56365 (2). 768. 
Endoscrinium sp. 


Ventral view of the specimen by phase contrast. BM(NH) slide V.56369 (1). 


Ventral view of same specimen, by ordinary light. x 48o. 


Dorsal view of same specimen showing the precingular archaeopyle. _ 480. 


x 640. 


14 


PEATE 


Bull. Br. Mus. nat. Hist. (Geol.) 21, 5 


FIG. 


PLATE 15 


Muderongia simplex Alberti 
I.G.S. slide PK 128. 720. 
Specimen showing the apical archaeopyle. I.G.S. slide PK 129. 922. 
Cleistosphaeridium sp. 

BM(NH) slide V.56367 (1). 720. 

Scriniodinium bicuneatum (Deflandre) 
BM(NH) slide V.56370. 752. 

Scriniodinium dictyotum subsp. osmingtonensis Gitmez 
BM(NH) slide V.52799 (1) sample OM 131. Holotype, without prominence at the 
apex. X47I. 
Scriniodinium dictyotum subsp. papillatum Gitmez 
Holotype, with precingular archaeopyle, showing the blunt, mammelon-shaped apical 
prominence. BM(NH) slide V.53940 (1). 480. 
Scriniodinium dictyotum subsp. pyrum Gitmez 

Specimen with strong apical horn. BM(NH) slide V.56371. 


Bull. Br. Mus. nat. Hist. (Geol.) 21, 5 PLATE 15 


Fic. 


Fia. 
Fic. 


Fic. 


Fic. 


Fic. 


Fic. 
Fic. 


con] 


PADI NANI; 1(6) 
Organism A 
BM(NH) slide V.53948 (3). General appearance. 691. 
Cavate cyst sp. indet. B 
I.G.S. shde PK 104. x 640. 
I.G.S. slide PK 106. x 640. 
Cavate cyst sp. indet. A 
1.G.S. slide PK 102C (3). 640. 
Pterospermopsis helios Sarjeant 
BM(NH) slide V.53963 (1). Sample SC 144 (Baylei Zone). 2100. 
Scriniodinium dictyotum subsp. dictyotum Cookson & Eisenack 
Specimen with a slight apical prominence. BM(NH) slide V.56372 (1). 496. 
Sirmiodinium grossi Alberti 
Dorsal view of specimen. BM(NH) slide V.56373 (1). 896. 
Specimen with apical archaeopyle. BM(NH) slide V.56374 (1). 941. 


Bull. By. Mus. nat. Hist. (Geol.) 21, 5 PLATE 16 


Fic. 

Eig. 2 
Fig. 3 
Fic. 4 
Fic. 5 
Fic. 6 
Fic. 7 
TGs 3 
FIG. 9 
Fic. 10 


PLATE 17 


Micrhystridium recurvatum Valensi 


EGS. slide PK 127, x1276; 


The other side of the same specimen. 1276. 


Organism A 


BM(NH) slide V.53948 (3). Phase contrast objective used. 768. 
Acritarch sp. indet. 
Specimen with opening. I.G.S. slide PK 125. x 1200. 


Another specimen with opening. 


I.G.S. slide PK 126. 


Pterospermopsis harti Sarjeant 


I.G.S. side PK 111. 1085. 


Micrhystridium sp. 
BM(NH) shde V.53953 (1). 1280. 
Phase contrast view of same specimen. 1280. 
Solisphaeridium claviculorum (Deflandre) 


I.G.S. slide PK tor. 1320. 
Phase contrast view of specimen. 


x 1320. 


x 1400. 


V7, 


PLATE 


Mus. nat. Hist. (Geol.) 21, 5 


Bull. Br. 


A LIST OF SUPPLEMENTS ~ 
TO THE GEOLOGICAL ‘SERIES 
OF THE BULLETIN OF | : 
THE BRITISH MUSEUM SS HISTORY) : 


Pps 213: 30 ‘Plates: 2 sa eri 706s ae 
. Et-Nacear, Z. R. Stratigraphy and Planlctovae Ronneaieat ° 
Cretaceous—Lower Tertiary Succession in the Esna-Idfu Regio 
Egypt, U.A.R. Pp. 291; 23 Plates; 18 Text-figures. 1966. 
. Davey, R. J., Downte, C., SARGEANT, W. A. S. & WILLIAM: 
Mesozoic and Cainozoic eee ieee ae ae 
figures. meee Sy fate 


Appendix to Studies on n Mesozoic ee Cainozoic Dinoflag 
1969. 8op. eos 
; ELLIOTT, Lee Permian to Pace me Ae @ us 
Middle East. Pp. 111; 24 Plates; 17 Text-figures. 1968, — 
. Ruopes, F. A Ls SosEy R.. L, & Drvce, E. Pes 1 Ee 


Pp. 315; 31 Pinter: 92 Tete heae 1969. fe ee 
. Cuitps, A. Upper Jurassic Rhynchonellid | "Brachiopetis om 
Europe. Pp. 119; 12 Plates; 40 Text-figures. 1969. i 

- Goopy, P. C. The relationships of -certain Upper 
special reference to the Myctopheid = 255; ween 


3 Plates: 52 Texthnie ‘Ig7T. fe: oe Ee 
. Sippigur, Q. A. Early Tertiary Oiees ee the cay Trachyleberic 
from West Pakistan. ae 98; 42 bene xe Bie go of EGYL eS ‘ 


abPLe 


JE8 Printed in England by Staples Printers Limited at their Kettering, Northants, establishment, 


-TERTIARY CYTHERETTINAE OF. 
_ NORTH-WEST EUROPE See” 


é KE » 
| 2 9 MAY i973 


aac .° 


£ ey 
& S 
Shay Wr 


_ BULLETIN OF 
MUSEUM (NATURAL HISTORY) 
Ree Vol. 21 No. 6 
_ LONDON : 1972 


x 


MID-TERTIARY CYTHERETTINAE OF 
NORTH-WEST EUROPE 


BY 


MICHAEL CHARLES KEEN_, 


Glasgow University 


Pp. 259-349; 23 Plates, 30 Text-figures 


BULLETIN OF 
THE BRITISH MUSEUM (NATURAL HISTORY) 
GEOLOGY Vor 21 No, 6 
LONDON : 1972 


THE BULLETIN OF THE BRITISH MUSEUM 
(NATURAL HISTORY), instituted in 1949, is 
issued in five series corresponding to the Departments 
of the Museum, and an Historical series. 


Parts will appear at irregular intervals as they become 
ready. Volumes will contain about three or four 
hundred pages, and will not necessarily be completed 
within one calendar year. 


In 1965 a separate supplementary series of longer 
papers was instituted, numbered serially for each 
Department. 

Ihlis paper is Vol. 21, No. 6 of the Geological 
(Palaeontological) series. The abbreviated titles of 
periodicals cited follow those of the World List of 
Scientific Periodicals. 


World List abbreviation 
Bull. Br. Mus. nat. Hist. (Geol.) 


© Trustees of the British Museum (Natural History), 1972 


TRUSTEES OF 
THE BRITISH MUSEUM (NATURAL HISTORY) 


Issued 29 December, 1972 Price £4.60 


MID-TERTIARY CYTHERETTINAE OF 


NORTH-WEST EUROPE 


By M. C. KEEN 


CONTENTS 


INTRODUCTION AND ACKNOWLEDGEMENTS 
LOCALITIES . 

STRATIGRAPHICAL DISTRIBUTION 5 
EVOLUTION OF MID-TERTIARY Caen 
ECOLOGICAL DISTRIBUTION OF RECENT SPECIES . 
PALAEOECOLOGY z 

GEOGRAPHICAL DISTRIBUTION . 


CLASSIFICATION OF THE SUBFAMILY CYTHERETTINAE . 


THE SHELL STRUCTURE OF CYTHERETTA 
SOFT PARTS . ‘ : 
LARVAL STAGES 
THE SHELL STRUCTURE OF FLE x US 
THE TYPE SPECIES OF CYTHERETTA 
SYSTEMATIC DESCRIPTIONS 

Order Podocopida Miiller 

Sub order Podocopina Sars 
Family Tvachyleberididae Sylvester Bradley 


Genus Cytheretta Miller . . A 
judaea (Brady) 2 = : 
subvadiosa (Roemer) 

costellata (Roemer) : 
costellata costellata (Roemer) 

costellata grandipora subsp. nov. 
costellata cvatis subsp. nov. 

costellata antecalva subsp. nov. 
bambruggensis Keij. 

crassivenia Apostolescu 

decipiens Keij 

aff. decipiens Keij 

haimeana (Bosquet) 

ruelensis Sp. NOV. 

eocaenica Keij 

oligocaenica sp. nov. 

geoursensis sp. Nov. 

cavita sp. nov. 

cellulosa sp. nov. 

aff. cellulosa 

Superspecies C. laticosta (Reuss) 

C. laticosta (Reuss) 

C. forticosta sp. nov. 

C. porosacosta sp. nov. 

Superspecies C. tenuipunctata (Bosquet) 
C. tenuipunctata (Bosquet) 

C. tenuipunctata tenuipunctata (Bosquet) 
C. tenuipunctata absoluta subsp. nov.. 


NANHHOHHAGHHAHAAHHAAADS 


Page 
263 
265 
207 
270 
272 
273 
274 
274 
277 
280 
280 
281 
281 
282 
282 
282 
282 


282 
283 
284 
285 
289 
289 
290 
291 
293 
293 
294 
294 
295 
295 
296 
297 
298 
299 
300 
301 
302 
304 
304 
304 
3097 
309 
309 
310 


262 MID-TERTIARY CYTHERETTINAE 
C. tenuipunctata livata subsp. nov. . ¢ : - < 311 
C. tenutstriata (Reuss) . : : j é c 312 
C. tenuistriata tenuistriata (Reuss) ° : é : . 312 
C. tenuistriata ornata subsp. nov. : : A . : 313 
C. minipunctata sp. nov. . : : 5 5; 5 : 314 
C. buttensis sp. nov. é é : ; : : 315 
C. buttensis buttensis subsp. nov. é : : : ‘ 316 
C. buttensis reticulata subsp. nov. : 5 : : 316 
Discussion of Superspecies C. pane : : : 318 
C, minoy (Lienenklaus) . : é : : ; ; 319 
C. posticalis Triebel : c c : : é ¢ 320 
C. posticalis posticalis Triebel : : . : : 320 
C. posticalis parisiensis subsp. nov. . : é : : 320 
C. headonensis Haskins . g : . : ¢ c 321 
C. vesca sp.nov. . c : 2 : : 5 : 322 
C. stigmosa Triebel . c 5 : 5 : : , 323 
C. stigmosa stigmosa Triebel_ . : : : ; : 323 
C. aff. stigmosa Triebel . > . : : : : 323 
C. stigmosa gallica subsp. nov. . : c é : : 323 
C. vegularis sp. nov. : : : : é : : 325 
C. bullans sp. nov. ; . é é ; : é 327 
C. sagri Deltel : : : : c : : : 327 
C. sagrvi sagvi Deltel 5 . 5 5 : : e 329 
C. sagyi inconstans subsp. nov. : : c : : 330 
C. sagyi martini subsp. nov. . ; < - . : 331 
C. samothracia Deltel 5 c : : : : 5 332 
C. minipustulosa sp. nov.. ; : ; 3 5 : 333 
C. gibberis sp. nov. . : : : 5 . . : 334 
C. postornata sp. nov. a c 5 3 c 5 : 336 
C. perita Deltel : 0 ; : 5 : c 336 
C. sculpta Ducasse c ° 6 ° : é : 337 
Cytherettasp. A. . . - : < ; : : 338 
Cytherettasp.B.  . = 5 : F ; : 338 
Cytheretta sp. C. . : 5 0 c . 5 ‘ 338 
Genus Flexus Neviani . - - - : : : 338 
F. plicatus (von Munster) D - 5 2 . 2 339 
F. concinnus (Triebel) . 5 : . : : c 339 
F. gutzwillevi (Oertli) . 4 : : : : F 340 
F. solentensis sp.nov. . 5 5 é : 340 
F. solentensis solentensis subsp. nov. . 3 . c c 340 
F. solentensis congestus subsp. nov. . “ 6 - : 341 
F. ludensis sp. nov. : : c : 5 : : 342 
F. lenijugum sp. nov. a a , c ; 9 : 343 
F. schoelleri (Keij) . c : : : : 5 : 344 
Flexus sp. A . : : 6 5 : : : : 345 
XV. CONCLUSIONS . ; : 0 5 < 5 : : 2 345 
SUMMARY 


Fifty eight species and subspecies of Cytheretta and ten of Flexus are described from the 
Middle and Upper Eocene and the Oligocene of western Europe. New species and subspecies are: 
from the Bartonian of the Paris Basin, Cytheretta costellata gyandipora, C. costellata cratis, 
C. carita, C. cellulosa, C. vuelensis, and Flexus ludensis; from the Upper Eocene of the Hampshire 


OF NORTH-WEST EUROPE 263 


Basin, C. costellata antecalva, C. forticosta, C. porosacosta, F. solentensis solentensis and F. solen- 
tensis congestus; from the Oligocene of the Paris Basin, C. tenuipunctata absoluta, C. tenui- 
punctata livata, C. tenuistriata ornata, C. minipunctata, C. buttensis buttensis, C. buttensis reticulata, 
C. posticalis parisiensis, C. vesca, and C. stigmosa gallica; and from the Oligocene of the Aquitaine 
Basin, C. oligocaenica, C. vegularis, C. bullans, C. gibberis, C. sagrt inconstans, C. sagyi martini, 
C. minipustulosa, C. postornata, and F. lenijugum. The stratigraphical distribution, ecology, 
and classification are also discussed. 


I. INTRODUCTION AND ACKNOWLEDGMENTS 


THE following study of the subfamily Cytherettinae is mainly concerned with Upper 
Eocene and Oligocene species, but also includes some from the Lutetian, from 
possible Miocene, and from the Pliocene and Recent. The area covered includes the 
Hampshire Basin, the Paris Basin, Belgium and the Aquitaine Basin. 

The study is taken from a Ph.D. thesis completed at the University of Leicester in 
1967. Since then the Geology Department has had a scanning electron microscope 
installed, and through the permission of Prof. P. C. Sylvester-Bradley it has been 
possible to re-photograph the ostracods. This has sometimes brought out characters 
which are not very clear under an optical microscope, and very high magnifications 
are possible which show features not visible at all with an ordinary microscope. 
The photographs were taken by Mr G. Mc. Turk, to whom thanks are extended. 

The stratigraphy of the Upper Eocene and Oligocene in Western Europe is 
complicated but the nomenclature of the stage names is even more so. There are 
some thirteen of the latter in common usage between the Lutetian and the Chattian, 
so to avoid confusion formation names are used where possible. When stage names 
are used however, they refer to the current usage in the particular area under dis- 
cussion. When two or more areas are mentioned, the classification adopted is 
that of Wrigley & Davis (1937). Recent reviews of the stratigraphy can be seen 
in Batjes (1959), Cavelier (1964, 1965), Curry (1965, 1966), and Vigneaux (1964). 

There are three main problems for the correlation of the mid-Tertiary within 
western Europe. The first is the relationship between the Middle and Upper Eocene; 
the second is the difficulty of recognizing the Bartonian in Belgium and the Paris 
Basin; and finally the placing of the Eocene-Oligocene boundary. Recent symposia 
at Bordeaux (1962), Paris (1968), and Marburg (1969) have failed to adopt any firm 
conclusions on any of these points. Most of the traditional concepts are under 
debate, and with so many ideas in the air correlation charts become redundant very 
quickly. Fig. 1 lists the horizons sampled for Cytheretta and also gives a tentative 
correlation. 

The species concept adhered to in this work is narrower than has perhaps been 
usual with Tertiary ostracods. The reasons for this are, first, that by studying one 
subfamily it is possible to follow its geographical and stratigraphical ramifications. 
Secondly, comparisons have been made with type material whenever possible. 
Finally, it is my belief that it is only through the detailed studies of small groups of 
ostracods that they will take their rightful place for use in Tertiary stratigraphical 
correlation, 


MID-TERTIARY CYTHERETTINAE 


264 


OLIGOCENE 


UPPER 
EOCENS 


MIDDLE 
EOCENE 


HAMPSHIRE 
BASIN 


PARIS BASIN; BELGIUM 
FALUNS D’ORMOY 


MORIGNYJARGILE DE BOOM 
JEURRE 


MARNES A HUITRES BERG _N.comta 


C. DE SANNOIS 
ARGILE VERTE TONGEREN HAMSTEAD BEDS 


SMARNES | OYSTER MARLS 
SUR RAey ie BEMBRIDGE LST. 


HEADON BEDS 


GY PSE 


BARTON BEDS 


\ 


MARNES A 
R ludensis 


SABLES MOYENS: 


UPPER 


MARINES 

CRESNES 

BEAUCHAMP BRACKLESHAM 
AUVERS BEDS 


SABLES DE WEMMEL 
Sy NeiUes) [pls Ls |pS 
SABLES DE BRUXELLES 


CALCAIRE 
GROSSIER 


MIDDLE 


RHINE 
oa am 


ASTRUP 
KASSEL 


RUPELTON ~ 
UNT. MEERESSAND 


MELANI ENTON~ 
LATDORF 


EOZAN V 


IASTERIES 


AQUITAINE 


ATAL AYE | 


MARNES 
BLEUES 


Correlation of Mid-Tertiary Beds in western Europe. 


Fie. 1. 


OF NORTH-WEST EUROPE 265 


I should like to record my grateful thanks to Prof. P. C. Sylvester-Bradley for his 
supervision throughout the work and for the use of the facilities of the Department 
of Geology at the University of Leicester. A study such as this also needs the 
cooperation of researchers in other countries, and I should particularly like to thank 
Dr H. J. Oertli, Mlle B. Deltel, the late Prof. J. Cuvillier, and Mme R. Damotte in 
France; Dr P. Marks in Holland; and Dr E. Triebel in Germany. The work was 
made possible by a N.E.R.C. NATO Research Studentship. The text-figures have 
been drawn by Mrs N. Farquharson. 

The ostracods described in this paper are in the collections of the British Museum 
(Nat. History) Palaeontology Department. 


il. LOCALIZIES 


Most of the samples used came from classical localities, either collected personally 
or donated by other workers. The sections are often poorly exposed, so few detailed 
measurements were taken. The relevant parts of some of the sections are given 
below. Other localities can be seen in Fig. 2. 


I. Cormeilles-en-Parisis (P.C.M.). 


This famous locality situated in the western suburbs of Paris reveals strata ranging 
from the marnes a L. inornata, through the gypsum beds, to the Couches de Sannois 
and Marnes a Huitres at the top. 

P.C.M.18—23; Couches de Sannois, sandy clays with shell bands. The samples 
come from beds 40, 42, 44, 45, 46, and 47 respectively of Albissin 
(1955). 


EC.M.24:; basal Marnes a Huitres. 

P.C.M.25; sandy clay 115 cm above base. 

P.C.M.26; oyster bed 230 cm above base. 

FC. M.27; Brown clay with Polymesoda immediately above oyster bed. 


2. Moiselles (PMS) 


A sand pit beside the RN I some twenty miles north of Paris. Sables de Beau- 
champ, Sables d’Ezanville, and Calcaire de St. Ouen are exposed. Only one sample, 
PMS.8, has yielded well preserved Cytheretta species; this is from the Sables de 
Beauchamp, 480 cm below the base of the Sables d’Ezanville. 


3. Marnes a P. ludensis of the Paris Basin. 


Two localities yielded ostracods: Chavengon and Verzy. At both localities the 
Marnes a P. ludensis is thin; about 150 cm at Chavengon, PCC.1 near the base, 
PCC.2 100 cm above; about go cm at Verzy, PVY.z2 at base, PVY.3 40 cm higher, 
PVY.4 30 cm higher still. 


266 MID-TERTIARY CYTHERETTINAE 


LONDON 
Bag! Re. 


; -~ oe Cness 


<< 


RHINE 


CHANNEL 7% 


CAS, AQUITAINE 
-BORDEAUX, BASIN 


Wie 
SCALE? (0 50 100 150 200 250 Km. 
BEE a) 


ke C EPS 
oe ee Palaeogene areas 
St Geours 
Zo eis Gaas ~ pe 


Fic. 2. Localities sampled for Cytherettinae. 


OF NORTH-WEST EUROPE 267 


4. Biarritz (RO). 
The cliff section at Biarritz exposes strata ranging from the Lutetian to the upper 


part of the Oligocene. Cytheretta species are described from the following samples, 
collected at the foot of the cliffs. No detailed section was measured. 


RO 264; base of the Couches de 1’Atalaye. 

RO 265; entrance to the tunnel at the Musée de la Mer. 

RO 266; southern end of the Grande Plage. 

RO 267; Rochers de la Villa Eugenie. 

RO 268; southern end of the Falaise lou Cout. 

RO 269, 270, 271; in ascending order below the Phare St Martin, collected over 
about 10 m of strata. 


5. Other localities in the Aquitaine Basin. 


(a) Bartonian clays of Lespontes. 

(b) Stampian of Gaas. Two localities were sampled, Espibos (AGE) and Les- 
barritz (AGL). The former of these is a completely overgrown quarry, where two 
samples were collected by digging, AGE.1 being slightly lower on the slopes than 
AGE.2z. At Lesbarritz, AGL.1 was from the cream marls exposed at the base of 
the section below the coral horizon. 

(c) St Geours de Maremne. The controversial locality at Escornbéou, which is of 
topmost Oligocene or lowermost Miocene age. 


6. Headon Beds of the Hampshire Basin. 


About 100 samples were examined; all cytherettinid species come from the Middle 
Headon Beds. Samples mentioned in the text are: Headon Hill, EHH.42, coming 
165 cm above the base of the Venus Bed; Whitecliff Bay, EWB(A) from the base of 
the Brockenhurst Beds, EWB(B) 10 cm higher, EWB.19 from 100 cm above the top 
of the Barren Sands, and EWB.22 100 cm above EWB.19. Other localities sampled 
are Colwell Bay, Milford, and Brockenhurst. 


7. Other localities. 


Bracklesham Beds of Selsey Bill, Whitecliff Bay, and Bramshaw. 

Auversian of Auvers-sur-Oise, and Le Ruel. 

Stampian of Auvers-St-George, St Cloud, Ormoy, and Morigny in the Paris Basin, 
and of Weinheim Trift in the Mainz Basin. 

Upper Oligocene of Astrup, near Osnabruck. 

Ledian of Bambrugge, Belgium. 


Ill. STRATIGRAPHICAL DISTRIBUTION 


The genus Cytheretta is probably the commonest ostracod genus found in the mid- 
Tertiary of north-west Europe. It often forms up to 30% of the ostracod fauna, 
with an average of about 15°%. The earliest species so far known is C. nerva Aposto- 


268 MID-TERTIARY CYTHERETTINAE 


lescu. This was originally described from the Sables de Bracheux (Thanetian) of 
the Paris Basin, but has since been recorded as the subspecies C. nerva montensis 
Marliére from the Montian of Belgium and Dutch Limburg (Marliére, 1958; Deroo, 
1966). C. multicostata Apostolescu is also found in the Sables de Bracheux. Other 
species are known from the London Clay (Ypresian) of the London and Hampshire 


C._bernensis 
C. buttensis 
. klahni ip AQUITAINE 

minipunctata <a 
C. minor Gaienese C. bullans 
C.posticalis C. minipustulosa C.regularis 
C. tenuipunctata C. postornata 
C. tenuistriata C.sagri : Csti 
C. triebeli C. samothracia C oligocaenica Somos 
C. variabilis C.vesca 


— 


C.rhenana 


RUPELIAN 


1 


S C.headonensis 
i|. 2) C. porosacostds a 
Wee N2 C.stigmosa 

1 


N 
\ a 
C.perita 


C laticosta (AQUITAINE) 


| 
| 
| 
| 
| 
| 
| : | ! 
z —S L ee 
| 
| 
C costellata | 
{ 
| 


C. bambruggensis | 
C costellata I 
C.crassivenia C decipiens C. forticosta ? 
C. haimeana 
C. ruelensis 


C costellata 
C. crassivenia Gicceipiene 
C. grignonensis “C.laticosta” Cc eocaenica 


C. haimeana i 
= — = = pe a ee, a eS eS ee 


C.carita 
| C.cellulosa 


C. eocaenica 
= 


| LUTETIAN | AUVERSIAN | BARTONIAN | 


C. crassivenia 4 re 
; C.laticosta 
C. scrobiculoplicata 


CUISIAN 


C. scrobiculoplicata “C.laticosta” ? 


YPRESIAN 


SPARNACIAN 
| 


C. multicostata | 
C. nerva | 


THANETIAN 


._C.montensis 2. \ 


iG nerva 


Paracytheretta 


= 


L 


bs MONTIAN 
= =TACEOUS|| DANIAN 
a 
| 
| 
lf 
| 
|) 


h 


Fic. 3. Suggested lineages of Cythevetta in northwest Europe. 


OF NORTH-WEST EUROPE 269 


basins (Jones 1956; Haskins, 1968; Eagar, 1965) and from the Sables de Cuise of the 
Paris Basin (Keij, 1957; Apostolescu, 1964). It is clear that Cytheretta is found near 
the beginning of the Tertiary, and it is necessary to look into the Cretaceous for its 
ancestry. 

The related genus Paracytheretta Triebel ranges from the Senonian to the Palaeocene 
(Morkhoven, 1963); the type species P. veticosa Triebel was described from the 
Middle Palaeocene of Denmark. Deroo (1966) has described four genera belonging 
to the subfamily from the Maastrichtian of Dutch Limburg. These include two new 
genera which are discussed in more detail below. Puri’s statement (1958) that 
Cytheretta stemmed trom Paracytheretta late in Palaeocene times therefore needs 
some modification. It would appear that the genus as now understood probably 
arose polyphyletically from late Cretaceous forms. Unfortunately Palaeocene and 
Lower Eocene species are not very well known, nor are Danian relatives, so it is 
impossible to discuss the origins of Cytheretta in any detail. It is not present in the 
well studied Maastrichtian faunas, but is in the Montian. The genus probably 
originated in western Europe, where it is most abundant, but it was already present 
in the Caribbean region during the Palaeocene (van den Bold, 1957), and also in 
Greenland (Szcezechura, 1971). 

Two distinct lineages can be seen amongst the early forms of Cytheretta (Fig. 3). 
The first is the superspecies C. laticosta (Reuss) which is found throughout the 
Eocene. The second is the more complicated group which includes C. nerva, 
C. scrobiculoplicata (Jones), C. crassivenia Apostolescu, C. costellata (Roemer), 
C. bambruggensis Keij, C. decipiens Keij, C. grignonensis Apostoiescu and C. haimeana 
(Bosquet). The last six of these are Middle Eocene species, although C. crassivema 
is also known from the Sables de Cuise (Lower Eocene). It was during Lutetian 
times that the group underwent a great explosion, both in numbers and in geo- 
graphical range. Several are found in the Auversian (Sables d’Auvers, Sables de 
Beauchamp), but apart from C. costellata did not survive into the Bartonian. The 
Upper Eocene was essentially a period during which the descendants of the Middle 
Eocene radiation continued to evolve. Compared with the Middle Eocene, the 
number of species is poor but individuals are abundant. A third group emerged 
during the Middle Eocene, exemplified by C. eocaenica Keij. The history of this 
group is fragmentary. Its ancestors are unknown; it is not found in the Upper 
Eocene of the region, yet in the Lower Oligocene of Aquitaine C. oligocaenica sp. nov. 
is found which is so close in morphology as to be separable only with difficulty from 
C. eocaenica. It is possible that this group was ancestral to the Oligocene groups 
and to the Miocene and Recent species of the Mediterranean. 

There were two distinct provinces in the Anglo-Paris region during the Eocene. 
The London Clay (Ypresian) of the western part of the London Basin has so far 
yielded only one common member of the genus, C. scrobiculoplicata, which is often 
extremely abundant (Eagar, personal communication). Bowen (1953) records one 
specimen of the C. laticosta group from Enborne, in the south-west London Basin. 
No younger species are known, however, because of the unfossiliferous nature of the 
succeeding strata. The London Clay of the Hampshire Basin also contains 
C. scrobiculoplicata, together with early members of the superspecies C. laticosta 


270 MID-TERTIARY CYTHERETTINAE 


(Haskins, 1968). For the remainder of the Eocene the superspecies C. laticosta is 
by far the most abundant Cytheretta. It is joined by C. haimeana, C. costellata, 
and C. eocaenica during the Middle Eocene, but in the Upper Eocene in most samples 
examined it is almost the sole representative of the genus. The Paris Basin formed 
the other province. During the Middle Eocene the C. haimeana group was common, 
no particular species being predominant; in the Upper Eocene however, C. costellata 
became completely dominant. In Belgium the picture is not clear, but it is ap- 
parently similar to the Paris Basin, although C. eocaenica is by far the commonest 
species in the Sable de Léde (Ledian). 

There was a certain amount of communication between these regions, because 
C. costellata is occasionally found in the Barton Clay (Bartonian) of the Hampshire 
Basin, while the superspecies C. laticosta is present in the Paris Basin and Belgium. 
The communication was much clearer during the Middle Eocene than during the 
Upper Eocene. 

The Oligocene saw an almost complete replacement of the Eocene species. New 
groups such as the superspecies C. tenuipunctata and C. sagri are dominant. The 
only groups with known Eocene ancestors are C. rhenana Triebel, C. stigmosa 
Triebel, and C. oligocaenica. The first two are related to species trom the Headon 
Beds of the Hampshire Basin, C. headonensis Haskins and C. aff. stigmosa Triebel, 
which in turn are probably related to C. eocaenica. C. oligocaenica is also related to 
the Middle Eocene C. eocaenica. This reflects the general situation amongst the 
ostracods, i.e. at the base of the Oligocene a completely new fauna is found in 
western Europe. Provinces existed, as in the Eocene, but with a different constitu- 
tion owing to palaeogeographical changes. The Paris Basin, Belgium, Mainz 
Basin, Rhine Graben and Swiss Basins formed one unit, and Aquitaine another. 
Within these are found sub-provinces due to geographical separation with the 
attendant evolution of distinct sub-species. 

The genus Flexus Neviani is first reported from the Sables de Cuise (Cuisian) of 
the Paris Basin (Apostolescu, 1964). Cytheretta decipiens was placed in the genus 
Flexus by Puri (1958), but tor reasons given below it is here retained in Cytheretta. 
However, this was probably the ancestor of F. concinnus (Triebel) (Keij, 1957; and 
see below). An undescribed species of Flexus has been observed in the Lutetian 
(Fisher Bed VII) of Whitecliff Bay, which is thought to have been derived from an 
early member of the superspecies C. laticosta. The genus is fairly common, though 
never abundant, in the Upper Eocene; it is represented by F. solentensis sp. nov. 
and F. ludensis sp. nov., the origins of which are unknown. In the Oligocene the 
genus is represented by F. concinnus; the type species F. plicatus (von Munster) 
comes from the Chattian. As used here, the genus is undoubtedly polyphyletic. 


IV. EVOLUTION OF MID-TERTIARY CYTHERETTINAE 


Various types of evolutionary pattern were exhibited by the Cytherettinae during 
Tertiary times. The C. haimeana species group is a good example of cladogenesis as 
defined by Sylvester-Bradley (1962). Using his terminology (Fig. 4) it is possible 
to recognize a first period of stabilization in the Palaeocene and Ypresian. During 


OF NORTH-WEST EUROPE 271 


5 SECOND PERIOD OF STABILITY 
4 DIVERSIFICATION 


3 ISOLATION AND RETICULATION 
2 ERUPTION 


] FIRST PERIOD OF STABILITY 


MIOCENE 


plicatus 


gutzwilleri 


OE GOCE NE 


| 
Flexus concinnus 


‘i 


38 


Le costellata costellata 
aff. decipiens antecalva cratis 


———— 


ruelensis 


= 
a 
in 
w 
> 
5 
= 


costellata 
= =; = grandipora 


| 
| 
| 


Za 
et 
Z 
[e) 
Re 
ac 
=z 
© 143 
oz 
Lt 
| mel 
| od 
uw 
ke 
=) 
— 


| bambruggensis 
__ aff. coStellata 
scroviculoplicata costellata 


Y PRESIAN 


scrobiculoplicata 


t 


multicostata nerva 


montensis 


PALAEOCENE 


Fic. 4. The evolution of the C. haimeana species group. 


272 MID-TERTIARY CYTHERETTINAE 


this lengthy period, gradual evolution (stasigenesis) was taking place whereby 
C. montensis gave rise to C. nerva, which in turn led to C. scrobiculoplicata. In the 
Upper Ypresian (=Cuisian) a period of eruption began which continued into the 
Lutetian. During this period seven new species appeared. Perhaps significantly 
this coincided with a transgression otf the sea, giving large areas of shallow marine 
waters ideal for Cytheretta, and presumably leading to a reduction in the selection 
pressure. The Middle Eocene (Lutetian and Auversian) was a time of extreme 
variation, and by the end of the Auversian most ot the species were extinct. The 
Bartonian saw a second period of stabilization, with two gecgraphical subspecies of 
C. costellata, and the descendants ot C. decipiens which were now almost generically 
distinct. Flexus s.s. appeared in the Oligocene, representing the last members of 
the group. Final extinction occurred in the Quaternary. Within the species group 
the evolution of the subspecies of C. costellata shows a pattern very similar to the 
classic Zaphrentis delanouei as interpreted by Sylvester-Bradley (1951). In the 
Lutetian, C. costellata costellata consisted almost entirely of one morphotype; great 
variation occurred in the Auversian, with seven morphotypes, followed by stabilisa- 
tion in the Bartonian where the subspecies consist mainly of one morphotype in each 
geographical region. 

As opposed to this pattern, the superspecies C. laticosta shows gradual evolutionary 
change, without any period of explosive evolution. 

A second period of eruption ot the Cytherettinae occurred near the base of the 
Oligocene, once again coinciding with the spread of shallow seas over much of 
Europe. The superspecies C. tenuipunctata shows great eruption in the Lower 
Rupelian, with the presence of many geographical subspecies. This was followed 
by stabilization in the Upper Rupelian and Chattian. 

Specific examples of evolution are dealt with in the taxonomic descriptions. 
These are C. costellata, C. eocaenica, C. laticosta, C. buttensis, C. sagri, and F. solen- 
tensis. 


V. ECOLOGICAL DISTRIBUTION OF RECENT SPECIES 


Three species are known from the Mediterranean: 

C. judaea (Brady) the type species, is described by Kruit (1955) from the marine, 
shallow water (5-15 m), sandy deposits of the Rhone delta; Puri, Bonaduce & 
Malloy (1965) report it being found in association with Posidonia meadows in shallow 
banks around the islands and peninsulars of the Gulf of Naples, where the salinity 
is about 38%, and the bottom water temperature 14-15°C; Rome records it from the 
shallow waters at Monaco (0-3 m) associated with Posidonia; Ascoli (1965) found it 
in waters up to 74 m deep in the Adriatic Sea. Brady originally recorded it from 
the coast of Syria. 

C. adriatica Ruggieri is apparently more restricted, but no details are available; 
it is found in beach sands at Rimini associated with C. judaea. 

C. belgica (Brady) is reported by Kruit (1955) trom the marine, sandy sediments 
of the Rhone delta in water of 10-15 m depth. These specimens may however be 
identical to C. adriatica. 


OF NORTH-WEST EUROPE 273 


Three species are present around the coasts of southern North America from the 
Bahamas, Florida, the Gulf coast and New York. These are C. edwardsi (Cushman), 
C. sahni Puri and C. tracy: Blake. C. sahni is reported by Hulings and Puri (1965) 
from a sand mud mixture in water less than 65 ft deep and with a salinity greater 
then 30%,. No details are known for the other two. 

In the same region two species of Protocytheretta are present: 

P. daniana Brady is reported by Puri and Hulings (1957) from clastic sediments at 
depths of 36-65 ft, more commonly in the deeper part; salinity, 28-35:6%% 9, clear 
water, temperature between 10° and 30°C; it is absent in the carbonate province of 
Florida. Curtis (1960) found it in sands, silts, and clays, particularly in water with 
an estuarine influence but predominantly marine; temperature 24-25°C. Kornicker 
(1965) mentions that it is found around the Bahamas. 

P. multicarinata Swain was recorded by Swain (1955) from the nearshore Gulf of 
Mexico. 

Cytheretta knysnaensis Benson is recorded by Benson & Maddocks (1964) from the 
Knysna estuary, South Africa, where it is found in muddy sands free from wave 
action but with a fair current; salinity is 28-4°%,, pH 8; it is associated with a partly 
marine and partly estuarine fauna. However, following the description of this 
species there are reasons for believing it may not be a true Cytheretta; the inner 
margin, radial pore canals and central muscle scars are different, there is a vestibule 
and an internal eye sinus, which Cytheretta does not have. 

To sum up, Cytheretta is normally found in shallow (10-30 m) nearshore clear 
waters of normal salinity; the temperature is warm (‘Mediterranean’) with a bottom 
water temperature of about 15°C; the substratum is a sand or sandy clay, often 
covered with seaweed. The genus Protocytheretta seems to be able to tolerate 
slightly brackish conditions with a salinity as low as 28%. 


VI. PALAEOECOLOGY 


The genus undoubtedly inhabited a similar environment during the Eocene as the 
recent species. This accounts for its abundance in the Tertiary of the Paris Basin, 
London Basin, Hampshire Basin, Belgium, Mainz Basin and the Swiss basins. 
These were all shallow water areas, except for the eastern part of the London Basin 
where the genus has not been recorded so far. The clear distinction between the 
London and Hampshire basins on the one hand and the Paris Basin on the other is 
probably in part geographical and in part related to the contrast between the sedi- 
ments of the two regions. In the former the ostracods are mainly found in argil- 
laceous deposits, while they are foundin arenaceous and calcareous depositsin the latter. 

The Upper Eocene of Biarritz has yielded only one or two specimens of Cytheretta, 
while Cytherella and Pontocyprella are extremely abundant. On the other hand, 
some inland exposures contain fairly abundant Cytheretta. The Oligocene of Biar- 
ritz also contains abundant Cytheretta. This is undoubtedly ecologically controlled. 
The Upper Eocene saw deep water at Biarritz which shallowed eastwards, eventually 
giving way to continental deposits; at the end of the Eocene the water shallowed 
with a change from argillaceous to arenaceous deposition. 


274 MID-TERTIARY CYTHERETTINAE 


The Headon Beds of the Hampshire Basin contain sediments deposited in a 
variety of environments ranging from freshwater to shallow marine. Ostracods are 
found in most of these environments, but Cythereita is restricted to the marine 
phases; as soon as brackish conditions prevailed Cytheretta disappeared. Thus it is 
found in association with such genera as Pterygocythereis, Tvachyleberidea, Bradleya, 
Leguminocythereis, Brachycythere and Haplocytheridea. ‘Whenever such genera as 
Neocyprideis or Cytheromorpha become abundant, Cytheretta is no longer present. 


VII. GEOGRAPHICAL DISTRIBUTION 


Fossil species have so far been reported from the Palaeocene, Eocene, Oligocene, 
Miocene, Pliocene and Quaternary of Europe; from the Palaeocene, Eocene, Oligo- 
cene, and Miocene of North America and from the Palaeocene of Greenland (Szcze- 
chura, 1971); Latham (1938) recorded Cytheretta costellata (Roemer) from the salt 
range, Punjab, but this is a misidentification and is probably a species of Buntonia. 
In space Cytheretta would appear to be restricted to the coasts of the North Atlantic 
and adjacent seas; the case of the South African C. kysnaensis has already been 
mentioned. Its greatest development is in Europe, where some hundred species, 
both fossil and recent, have been described. 

Flexus has only been reported from western Europe where it ranges from the 
Lower Eocene to the Quaternary, the latest recorded species being F. tviebeli Ruggieri 
from the Upper Pliocene and Lower Quaternary of Italy (Ruggieri, 1952). 

Protocytheretta is restricted to North America where it ranges from the Oligocene 
to Recent. Itis found in the Gulf of Mexico, and also off the west coast of California 
and Mexico (Swain, 1969). 

Recently described genera are mainly known from their type areas only. Thus 
Acuticytheretta and Semicytheretta are only known from western Europe, while 
Bensonia, Grekoffiana, and Argenticytheretta are only recorded from south America. 
For a discussion of these see the next section. 


VIII. CLASSIFICATION OF THE SUBBAMILY CYTHERETLINAE 


Following Hazel (1967) the Cytherettinae are regarded as a subfamily of the 
Trachyleberididae ; this based on the muscle scars, hinge, and soft parts. 

The following genera have been included by various authors within the subfamily: 
Cytheretta Muller, 1894; Flexus Neviani, 1928 (syn. Eucytheretta Puri, 1958) ; Pseudo- 
cythereis_ Skogsberg, 1928; Buntonia Howe, 1935; Paracytheretta Triebel, 1941; 
Loculicytheretta Ruggieri, 1954; Ambocythere Van den Bold, 1957; Protocytheretta 
Puri, 1958; Netrocytheridea Howe and Laurencich, 1958; Neocytheretta Morkhoven 
1963; Acuticytheretta Deroo, 1966; Semicytheretta Deroo, 1966; Bensonia Garcia, 
1969; Grekkofiana Garcia, 1969; and Argenticytheretta Garcia, 1969. 

Loculicytheretta was placed in the subfamily by both Ruggieri (1954) and Howe 
(Treatise, 1961), but its distinctive characters would seem to exclude it. Deroo 
(1966) placed Netrocytheridea into the subfamily ; however its shape and entomodont 
hinge would appear to exclude it. The only real similarity is in the irregular shape 


OF NORTH-WEST EUROPE 275 


of the inner margin. Ambocythere was included by Morkhoven (1962, 3) because 
of its supposed ressemblance to Buntonia; its false radial pore canals, branching 
radial pore canals, and lateral shape do not support its inclusion. Neocytheretia from 
Indonesia is not considered to belong to the subfamily. It has eye spots (Cytheretta 
is blind), a completely different type of ornamentation, and a different hinge; only 
the irregular inner margin resembles Cytheretta. 

Pseudocythereis was placed in the subfamily by Puri; no material has been available 
for study, only the original description of Skogsberg could be examined. The type 
species is Cythereis (Pseudocythereis) spinifera Skogsberg, and the author was un- 
doubtedly comparing it with C. rubra Miller as far as the soft parts were concerned, 
but the description of the shell is inadequate. Therefore, no conclusion could be 
reached concerning it, except to agree with Puri that there are strong resemblances 
to Cytheretta. 

Paracytheretta has a very well developed anterior hinge ear in the left valve and no 
other Cytheretta species approach it in this respect. The hinge is apparently similar 
to Cytheretta (Morkhoven, 1963), the surface of the valve is reticulate with three 
longitudinal ridges. 

The development of three longitudinal ridges is a common feature of the subfamily, 
but not all such forms are necessarily closely genetically related. Puri recognized 
three such genera, Paracytheretta, Eucytheretta, and Protocytheretta. The latter was 
said to be Cytheretta-shaped, while the others were Cythereis-shaped; the first two 
were then differentiated on the hinge, which is Cytheretta-like in Eucytheretta and 
Cythereis-like in Paracytheretta. However, Triebel’s original description of the hinge 
of Paracytheretta, as shown by Morkhoven (1963) is the same as for Cytheretta. There 
is, however, no doubt that Paracytheretta is a valid genus because of its distinctive 
shape. Flexus has a totally different shape, much more like that of Cythereita. 
Flexus and Protocytheretta can be separated, both on shape and ornamentation. 
The only species studied that Puri placed into Protocytheretta is P. schoellert Keij 
from the Oligo-Miocene of Aquitaine; apart from this species the genus would be 
restricted to North America. A study of descriptions and illustrations of P. daniana, 
the type species, suggests that P. schoelleri does not belong to the same genus, and 
therefore, that the genus is probably restricted to North America (see description 
and discussion in P. schoelleri below). 

Flexus has already been shown to be polyphyletic. It is used here for all species 
shaped like the type species, F. plicatus (von Munster) and having three prominent 
longitudinal ridges. This is not a very satisfactory arrangement, but present 
knowledge makes it very difficult to divide it into new genera. 

Similarly, no attempt has been made to further subdivide the genus Cytheretia. 
As mentioned above, there are six distinct groups in the Eocene and Lower Oligocene 
of western Europe. However, the recognition of such monophyletic groups is 
difficult to correlate with easily diagnosed morphological characteristics, so it has 
been thought better for the present to limit their taxonomic recognition to the rank 
of superspecies. Further investigation, particularly of Lower Tertiary forms, should 
lead to a phylogenetic division of the genus; this must be combined with a study 
of the American species, and so is beyond the scope of the present work. 

B 


276 MID-TERTIARY CYTHERETTINAE 


The six groups mentioned above are: 

. haimeana group 

. laticosta group 

. cocaenica group 

. tenuipunctata group 
. sagryt group 

. rhenana group 

Acuticytheretta certainly has a Cytheretta-like appearance in general outline, has 
unequal valves and similar muscle scars to Cytheretta. The inner margin is very wide 
posteriorly, but not irregular; and the hinge is simpler, with a large anterior tooth 
in the right valve, and a small anterior tooth at the end of the smooth (?) bar of the 
left valve, and a posterior tooth in the right valve. It could represent a primitive 
member of the subfamily. 

Semicytheretta has a similar hinge and muscle scars to Cytheretta, but has a narrow 
and regular inner margin and a different shape. 

Deroo also describes Cythere euglypha Bosquet and Cythereis euglyphoidea Van 
Veen, which from the illustrations could also be included in the subfamily. Their 
shape, unequal valves, muscle scars, and ornamentation suggest this; the hinge has 
faintly crenulate anterior and posterior teeth in the right valve, and the inner margin 
is narrow and regular. They are placed in the genus Anticythereis Van den Bold. 
These could be early primitive members of the subfamily. 

Morkhoven (1962, 3) included Buntonia in the subfamily because the first thoracic 
legs of the male are similar to those of Cytheretta. In general appearance certain 
Buntonia species can be confused with cytherettinids, although there are noticeable 
differences in the hinge and the inner margin. It is provisionally included within 
the subfamily. 

Grekoffiana is described as being similar to Protocytheretta, but with a regular inner 
margin. The type species is G. australis Rossi de Garcia. In the discussion of the 
new genus (1969; 218), de Garcia placed Protocytheretta daniana (Brady) Benson 
and Coleman in Grekoffiana. This might be taken to imply the species as interpreted 
by Benson and Coleman, and not Brady’s species; on page 220 we have mention of 
‘Grekofiiana daniana (Brady) dans Benson et Coleman (1963) (p. 26, Tab. 5, Figs 
5, 7, 9 & 10)’; again, perhaps implying the species as interpreted by Benson and 
Coleman, but in this case there should have been some statement to this effect. The 
idea is thus given that Brady’s species is being included in the new genus, even 
though it is in fact the type species of Protocytheretta. P.danianais generally thought 
of as having a typical cytherettinid sinuous inner margin, although following Benson 
and Coleman it may in fact show considerable variation. Thus two problems arise: 
firstly, if P. daniana can have a regular or a sinuous inner margin, 1.e., it is an infra- 
specific character, it can hardly be used to diagnose a new genus; and secondly, the 
type species of a genus cannot be included in a new genus. There are grounds then 
for wondering whether Grekoffiana is in fact a valid genus, and not a synonym of 
Protocytheretta. 

Bensonia is described as being similar to Cytheretta, but with a regular inner 
margin. The hinge and overall appearance certainly look like a typical cytheret- 


AANA AO 


OF NORTH-WEST EUROPE 277 


tinid. Cytheretta knysnaensis is placed in this genus, and as stated previously, there 
are certain features, particularly the implied presence of an eye, which would exclude 
it from Cytheretta. The presence or absence of any occular structures cannot be 
determined from Rossi de Garcia’s description, so it is difficult to know whether 
Bensomia is a true cytherettinid genus. It is provisionally placed in the subfamily. 
Argenticytheretta is illustrated with what appears to be an eye tubercle, and in 
overall shape does not resemble Cytheretta. It also has a regular inner margin. 
From this it would seem that there exists a group of Cytheretta-like ostracods, 
principally occurring on the two sides of the south Atlantic, but which differ from 
true cytherettinids in several respects. Perhaps it is a case of homeomorphy? 
Until more species are described in detail, this question must remain unanswered. 
The genera included within the subfamily are: 


Cytheretta 
Flexus (syn. Eucytheretta) 
Paracytheretta 
Protocytheretta (syn. Grekoffiana?) 
Acuticytheretta 
Semicytheretta 

Provisionally: Buntonia 
Pseudocythereis 

Doubtfully: Bensonia 

Argenticytheretta 


The characters taken to be diagnostic of the Cytherettinae are: inequivalve, the 
left valve being markedly larger and differently shaped than the right; a modified 
holamphidont hinge; presence of a fulcral point; numerous and simple radial pore 
canals; generally sinuous inner margin; unornamented, or with a predominantly 
longitudinal ornamentation; development of few posterior spines and many anterior 
denticles ; lack ot occular structures, lateral spines, and caudal process. 


IP EPS rn Li SrieUC RUB Om CY ie RE na A 


Cytheretta typically has an elongate-ovate shape. The dorsal margin is straight to 
convex, often with a posterior hinge ear and sometimes with an anterior hinge ear 
in the left valve. The posterior margin is obliquely curved with a sharp, high 
postero-dorsal angle and a gentle slope round to the ventral margin. The latter is 
often concave, always so in the right valve. The valves are usually very unequal 
in size and shape, the left valve being much larger and with a greater height; in 
lateral view the outline of the left valve over-reaches that of the right valve in most 
places. This over-reach is particularly prominent in the postero-dorsal angle where 
the hinge ear is developed and in the anter-dorsal angle where the antero-dorsal lobe 
(see below) of the hinge of the left valve rests on the antero-dorsal platform of the 
right. The shape in dorsal view varies. Sexual dimorphism is distinct, the males 
being more elongate. 

The carapace may be completely unornamented, as in the type species. More 
usual, however, is an elongate ornamentation which can take the form of either 


278 MID-TERTIARY CYTHERETTINAE 


longitudinal rows of pits, usually better developed towards the posterior, or longi- 
tudinal ridges. The latter often have reticulation developed between them, and 
some ridges converge to form a sub-central plexus (Fig. 5). For descriptive purposes 
the ridges are numbered from the dorsal margin in a position just to the posterior 
of the sub-central plexus (Fig. 5). The anterior and antero-dorsal regions of both 
valves are often smooth, while the rest of the carapace is ornamented. The orna- 
mentation is generally similar for both valves. 

The hinge is modified holamphidont with several accessory elements (Fig. 6, 7; 
Plates 5, 7,8). In the left valve there is an anterodorsal lobe, which is an outgrowth 
of the selvage and rests on to an antero-dorsal platform in the right valve. The 
anterior socket is partially opened ventrally; it is bordered by an antero-ventral 
lobe which fits into the modified anterior part of the anterior tooth of the right valve, 
the antero-ventral sinus, which is a hollow in the tooth. The antero-median tooth 


719 


SS Ste 


Fic. 5. C. costellata (Roemer), showing the system of numbering the ridges. X75. 


is generally small, the postero-median bar is crenulate and swollen at the posterior 
to give a postero-median swelling. This is sometimes almost as prominent as the 
antero-median tooth, as in the type species; it forms one edge of the posterior socket, 
which is almost open ventrally. The posterior socket often forms a posterior hinge 
ear, sometimes with a lobe. In the right valve the anterior tooth has an almost 
vertical face towards the anterior; it is sometimes stirpate (=stepped), or with a 
gentle posterior slope. In lateral view the tooth has a concavity in the antero- 
ventral position, the antero-ventral sulcus. The antero-median socket is shallow, 
the postero-median groove is crenulate, and there is usually a shallow postero- 
median socket. The posterior tooth is generally pessular (i.e. with more or less 
parallel sides) and is sometimes almost as prominent as the anterior tooth, as in the 
type species. 

There is considerable variation in the details of the duplicature. The selvage is 
generally more prominent in the right valve. At the anterior it usually has a position 
close to the outer margin, but in some species it is further away so that a prominent 
flange groove is formed; there is a wide flange groove developed along the ventral 
margin of the right valve, with a narrow one along the posterior. The selvage is 


OF NORTH-WEST EUROPE 279 


Py packs: 
I vl. HINGE IN DORSAL VIEW 
; Postero-median Y> Antero- median 
Postero -median bar tooth 


swelling 


Posterior 
socket 
eee Anterior 
radia Radial 
pore canals pore canals 


dm. Dorsal muscle scars 
Selvage am. Adductor muscle scars 
fm, Frontal muscle scar 
f. Fulcral point 
Left Valve as. Anterior socket 
avi. Antero-ventral lobe 
np. Normal pore canals 


Fic. 6. Internal structure of the left valve of Cytheretia. 


HINGE IN DORSAL VIEW 


Antero-  Postero- = Postero- ~Posterior 
Antero-dorsal Anterior median median median tooth 
platform tooth socket groove socket 
Fl 
Bae eoeove Antero-ventral 
sinus 
I 
Anterior re : 
indentation Ventral indentation 
| Posterior Posterior 
een Bedian \ ape ment indentation 
\segment | segmen of inner 
Flange g Crlvage g ewe i 


Flange 


Flange groove 


Right Valve 


Fic. 7. Internal structure of the right valve of Cytheretta. 


280 MID-TERTIARY CYTHERETTINAE 


sometimes very strongly developed at the posterior. The flange usually forms the 
outer margin. A weak list is often present. 

The outline of the inner margin is a characteristic feature; it is broad with three 
principal indentations (Fig. 7); its outline can be divided into three segments for 
descriptive purposes. It ends against the anterior and posterior hinge elements. 
The anterior and ventral radial pore canals are long, simple, often crossing one 
another, usually bulbous near the outer margin (Pl. 1). The anterior pore canals 
tend to be concentrated around the antero-ventral angle. The posterior radial pore 
canals are rather different (Pl. 1, Fig. 9); the inner lamella in which they are situated 
is not fused to the outer lamella, so that a vestibule is in fact formed. The posterior 
radial pore canals are numerous, straight and very closely packed; often they form 
two groups, a ventral one of short pore canals similar to the anterior and ventral 
radial pore canals, and a dorsal one of closely packed pore canals. 

The central group of muscle scars consists of a row of four adductors; the lower 
two often touch and the third one often elongate; and a large irregularly “U’-shaped 
frontal scar with a smaller scar in front. A fulcral point is prominent, forming a 
raised boss; this feature is also a well known characteristic of the Cytherideinae 
(von Morkhoven, 1963). A dorsal group of about three muscle scars can be detected. 
There are two mandibular scars which almost touch, or one elongate scar near, and 
just anterior to, the ventral indentation (Pl. 1, Fig. 7). 

There is no eye spot or occular sinus, as Cytheretta is blind. The feature often 
described as an eye spot is the antero-dorsal lobe of the hinge of the left valve. 


x, SORT PARTS 


The soft parts have not been examined during this study, and the only published 
descriptions are for C. rubra, C. edwardsi (Cushman) 1906 and C. tracyi Blake, 1929 
(Hazel, 1967). The principal characters ‘are the three-jointed exopodite of the 
second antennae, absence of a seta on the posterior border of the protopodite of the 
first thoracic legs’ (Hazel, 1967; 40, after Miller, 1894) and an asymmetry of the 
first pair of thoracic legs in the male which is developed to varying degrees. 


XI. LARVAL STAGES 


Only the last three larval stages have so far been recognized. They tend to be 
more triangular in shape, with a pointed posterior. Ornamentation in the last 
moult is similar to that of the adult, but in earlier moult stages is only partially 
developed. The hinge is very simple; in the left valve the antero-dorsal lobe is 
developed, followed by an anterior socket open ventrally, smooth bar and posterior 
socket, also opened ventrally; the corresponding features are present in the right 
valve. 

About one in fifty of the adult specimens appears to be weakly calcified. The 
hinge is an adult hinge, but weak; the inner margin is straight, without the normal 
indentations, and very narrow. Pokorny (1965) suggested that such a feature might 
be due to a parasitic infection and Morkhoven (1963) that the animal died soon after 
moulting and before calcification was complete. Oertli (1965) mentions the case of 


OF NORTH-WEST EUROPE 281 


Falumia where the true adult form is very rare, and the thinly calcified moult stage 
was probably mature, i.e. a case of neotony. Sandberg (1965) supported this by 
citing cases where such immature forms contained eggs. However, in the case of 
Cytheretta Morkhoven’s explanation is probably the correct one. 

In two species, C. eocaenica and C. oligocaenica, a few very large specimens are 
found. They are about double the size of the normal adult, but otherwise identical. 
This is a fairly frequent phenomenon in several families of the Ostracoda. Benson 
(1965) suggests that such forms might be a gerontic stage; and Kesling in the Treatise 
(1961) considers that they represent post-maturation instars. 


SITs ARIEhd; SIRT IVI Salix Oed, (ON 1a IT>,<10/s) 


Internal details are the same as for Cytheretta. As defined here, all Cytheretta-like 
forms with three prominent longitudinal ridges are referred to this genus. 


SO eh sh Vere Shel s Ol (OY irr Reo WA 


Miller described Cytheretta in 1894 with C. rubra Miller as type species. In 1950 
Ruggieri put C. rubra into the synonymy of C. subradiosa (Roemer), originally 
described from the Pliocene of Italy. This was accepted by Triebel (1952), Puri 
(x958) and Hazel (1967), but queried by Morkhoven (1963). Thanks to Prof. 
Ruggieri, who kindly supplied the material, it has been possible to study both forms. 
Morkhoven also mentioned that C. rubra might be a synonym of I/yobates? judaea 
Brady, 1868; Hazel accepted this view, but places both C. rubra and C. judaea within 
the synonymy of C. subradiosa. Fortunately Brady’s material is preserved in the 
collections of the Hancock Museum, No. B67, presently under the care of Dr. 
K. McKenzie. There is no doubt that C. judaeais the senior synonym. The problem 
now is whether this is synonymous with C. subradiosa. 

C. subradiosa was described from the Pliocene of northern Italy at Castellarquato ; 
none of Roemer’s material is available for study, but Ruggieri has obtained topotype 
material. The specimens described below come from the Pliocene of San Arcangelo, 
near Rimini. Miller’s specimens were from the Gulf of Naples; the specimens des- 
cribed below come from the beach sand at Rimini. 

A comparison of the Pliocene specimens with the recent has shown a number of 
differences which are believed to distinguish C. judaea from C. subradiosa. The 
position of the Quaternary forms is unknown. 

The major difference is in the line of the inner margin, particularly the posterior 
segment. In C. judaea this cannot be separated from the median segment, but in 
C. subradiosa it is steep, giving a narrow and deep posterior indentation ; the posterior 
indentation in C. judaea is very broad. There are more radial pore canals in 
C. subradiosa, 32 compared with 24 in C.judaea. The central muscle scars are situated 
more to the dorsal in C. subradiosa; the four adductors are larger and the frontal is 
more dorsally situated in respect to the adductors. There is a slight difference in 
shape in that C. judaea is more obliquely rounded in the anterior margin. The hinge 
is almost identical although the anterior tooth of the right valve is slightly more 
prominent in C. judaea. 


282 MID-TERTIARY CYTHERETTINAE 


Finally, Muller included two distinct species in his description of C. rubra (see 
below). One is probably synonymous with C. judaea and the other with Cytheridea 
striatopunctata Terquem 1878. 


XIV. SYSTEMATIC DESCRIPTIONS 
Subclass OSTRACODA Latreille, 1806 
Order PODOCOPIDA Miller, 1894 
Suborder PODOCOPINA Sars, 1866 
Family TRACHYLEBERIDIDAE Sylvester-Bradley, 1948 
Subfamily CYTHERETTINAE Triebel, 1952 


Genus CYTHERETTA Miller, 1894 


1894 Cytheretta Miller, p. 382 

1906 Pseudocythevetta Cushman, p. 382 
1928 Cylindrus Neviani, p. 106 

1941 Prionocytheretta Mehes, p. 60 


Dracnosis: The carapace is elongate-ovate, with a gently curving postero-ventral 
angle so that the posterior margin is markedly asymmetrical. Generally very 
inequivalve, with a large left valve. Ornamentation consists of longitudinal ridges 
or rows of pits, or the carapace may besmooth. The hinge is modified holamphidont. 
The line of inner margin is sinuous; the duplicature is wide; selvage, flange, and list 
are developed to varying extents; the radial pore canals are simple, long, bulbous, 
and curved; the normal pore canals are simple. The central muscle scars consist of 
a row of four adductors and a large irregularly ‘U’-shaped frontal; a fulcral point is 
well developed. 


TYPE SPECIES: Ilyobates? judaea Brady. 


Discussion: The type species of Cylindrus is C. jurinei (von Munster) which is a 
true Cytheretta; the name Cylindrus is also preoccupied (Fitzinger, 1833, Mollusca). 
Neither of the other two have been studied; Puri (1958) states that the shell structure 
of Pseudocytheretta is identical with that of Cytheretta, and Hazel (1967) discusses the 
genus in some detail and concludes that it is synonymous with Cytheretta. Triebel 
(1952) places Prionocytheretta in the synonymy of Cytheretta. 


OF NORTH-WEST EUROPE 283 


Cytheretta judaea (Brady) 
(Pl. 1, fig. 1, 4-7, 9; Text Fig. 8) 


1868 Ilyobates ? judaea Brady: 112, pl. 13, figs 17, 18. 

1894 Cytheretta vubra Miller: 382, pl. 8, figs. 9, 10, 16; pl. 39, figs 8-22, 24. 
1912 Cytheretta vubya Miller; Miiller: 366. 

1950 Cytheretta subyadiosa (non. Roemer; pars); Ruggieri: 9. 

1953 Cytheretta subvadiosa (non. Roemer; pars); Ruggieri: 102. 

1955 Cytheretta vubya Miller; Kruit: 482, pl. 5, figs 9a—c. 

1958 Cytheretta subyadiosa (non. Roemer; pars); Puri: 186, pl. 1, figs 3-7. 
1959 Cytheretta subvadiosa (non. Roemer; pars); Ruggieri: 190. 


Diacnosis: A species of Cytheretta with sub-parallel dorsal and ventral margins 
and unornamented surface. The inner margin is almost straight. 


MATERIAL: Thirteen valves and carapaces from the beach sand at Rimini; 
Io 3792-4; 3810. 
TYPE LOCALITY AND HORIZON: Haifa, Recent. 


STRATIGRAPHICAL RANGE AND DISTRIBUTION: Recent—Rhone delta, Monaco, 
Naples, Adriatic Sea, Syria, Aegean Sea; Quaternary of Italy? 


DESCRIPTION: Sexual dimorphism is not strong; the males are more elongate. 
Sex ratio 1:5. The left valve has a weak posterior hinge ear; the dorsal margin is 
slightly convex; the anterior margin is strongly obliquely rounded. The ventral 
margin is almost straight and roughly parallel to the dorsal margin; the posterior 
margin is obliquely rounded. The greatest height is just to the posterior of centre. 
The ventral margin of the right valve is concave. In dorsal view the carapace is 
ovate, tapered towards the anterior. 

The shell is smooth, but with conspicuous opaque areas; there is a large one in the 
central region and a smaller one in the anterior. These are approximately constant 
in position in all specimens, producing the black areas seen in PI. 1, fig. 4. 

The antero-dorsal lobe of the hinge of the left valve is flat; the postero-median 
swelling is pronounced. In the right valve the posterior tooth is almost equal in 
prominence to the anterior tooth. 


Fic. 8. Cytheretta judaea (Brady); left valve; x75. 


284 MID-TERTIARY CYTHERETTINAE 


The anterior indentation of the inner margin is wide and downward pointing; the 
anterior segment is gently curved; the median and posterior segments cannot be 
separated; the posterior segment is large and broadly rounded. There are some 
24 anterior, 27 ventral, and 32 posterior radial pore canals. The posterior set can 
be divided into two groups; a ventral group of ten, widely spaced and bulbous, and a 
dorsal group of 22, very close together and straight. There are some 75 scattered 
normal pore canals. The selvage is close to the outer margin, with a flange groove 
along the ventral margin. 


DIMENSIONS: 
Left valve Right valve Carapace 
ie H L/H i H L/H Ww 
Female 0-75 0°43 174) 0-75 0:40 1°88 0°42 
Male 0-79 0°43 1:84 0-78 0-39 2°00 0-40 


Discussion: Miller (pl. 8, fig. 13) and Puri (pl. 1, figs 9-13) illustrate large speci- 
mens with longitudinal rows of puncta. These must represent a different species; 
as well as the differences already mentioned, the anterior margin is much squarer than 
the obliquely rounded C. judaea. Triebel (1952; 17) suggests that these belong to 
Cytheridea striatopunctata Terquem, described by Terquem (1878) from the Pliocene 
of Rhodes. Several specimens of this type were found in the sample from Rimini, 
and were first thought to belong to C. adviatica Ruggieri; however, none have such 
strong longitudinal ridges as those illustrated by Puri (1958, pl. 2, figs 1-5). They 
are perhaps members of a gradational series in which C. adrviatica represents the mor- 
photype with the strongest developed ornamentation. 

See also the generic discussion (p. 281). 


Cytheretta subradiosa (Roemer) 
(Pir, fig? 8) 


1838 Cytherina subyadiosa Roemer: 517, pl. vi, fig. 20. 

1880 Cytherella calabra Seguenza: 326, 366, pl. 17, fig. 56. 

1900 Cytheridea subyadiosa (Roemer); Namias: 105, pl. 15, fig. 17. 
1905 Batrdia subyadiosa (Roemer); Cappelli: 306, pl. 9, fig. 4. 
1928a Cythevidea subyadiosa (Roemer) ; Neviani : 66. 

1928b Cytheridea subradiosa (Roemer); Neviani: 131. 

1950 Cytheretta subvadiosa (Roemer); Ruggieri; 9-11 (pars). 

1953 Cytheretta subvadiosa (Roemer); Ruggieri: 102 (pars) 

1959 Cytheretta subradiosa (Roemer); Ruggieri: 190 (pars). 


DiaGnosis: An unornamented species of Cytheretta with sub-parallel dorsal and 
ventral margins. The inner margin has a steep posterior segment. 


MATERIAL: Five carapaces and valves, together with several fragments, from the 
Lower Pliocene of San Arcangelo, near Rimini. Io 3795. 


TYPE LOCALITY AND HORIZON: Castellarquato; Pliocene. 


STRATIGRAPHICAL RANGE AND DISTRIBUTION: Pliocene of Sicily, Calabria, Castel- 
larquato, and Rimini; Quaternary of Italy? 


OF NORTH-WEST EUROPE 285 


DEscrRIPTION: The left valve has a very weak posterior hinge ear; the dorsal margin 
is almost straight, although in some specimens there is a distinct convexity in the 
central region which interrupts the smoothness of the margin. The anterior margin 
is obliquely rounded. The ventral margin is straight in the presumed females, but 
concave in the one specimen thought to be a male. The posterior margin is broadly 
rounded. The right valve has a greater height towards the posterior; the ventral 
margin is concave. The carapace is ovate in dorsal view. 

The shell is smooth, with no ornamentation. 

The hinge of the left valve has a flat antero-dorsal lobe; the antero-ventral lobe is 
weak; the postero-median swelling is pronounced and equal in size to the antero- 
median tooth. In the right valve the posterior and anterior teeth are equal in size. 

The anterior indentation of the inner margin is wide and downward pointing; the 
ventral indentation has a flat base instead of the usual ‘V’ shape; the posterior 
indentation is narrow, deep and curved. The anterior segment is almost straight; 
the median segment is slightly irregular, with a gentle upward slope towards the 
posterior; the posterior segment is very steep. There are some 32 anterior, 34 
ventral, and 32 posterior radial pore canals; and 25 scattered normal pore canals. 
The selvage runs very close to the margin; there is a small flange groove along the 
ventral margin. 


DIMENSIONS: Carapace 


Bb H Ww L/H 
Female 0°75 0°45 0:37 1-67 
Male 0-81 0°44 0:36 1°84 


Discussion: From the few specimens studied, there would appear to be consider- 
able variation in shape. See also the generic discussion (p. 281). 


Cytheretta costellata (Roemer) 


DiacGnosis: A species of Cytheretta with a characteristic ornamentation of ten 
longitudinal ridges which unite and bifurcate in a regular pattern; posterior margin 
with four strong spines, anterior margin with some nine denticles. Strongly 
inequivalve. Duplicature with an anterior flange groove and a ventral list. 


DESCRIPTION: Seven morphotypes have been recognized, chiefly on ornamentation. 
These are described below. 

The ornamentation consists of ten longitudinal ridges with varying ornamentation 
between (see Text-fig. 5). The second ridge bifurcates towards the posterior and the 
lower part eventually joins ridge no. 3; from the junction a thin ridge runs into no. 4. 
Ridge no. 4 is prominent, and forms the dorsal limit to the subcentral plexus towards 
the anterior. No. 5 forms the ventral limit and again is prominent; in the posterior 
of the valve it joins no. 7. No. 6 appears to be enclosed between 5 and 7, and joins 
one of these two. No. 7 is very prominent and extends further towards the posterior 
than any other; 8 and g join together in a position level with the sub-central plexus, 
9 bifurcating just to the posterior. An area of reticulation of varying size is present 
at the anterior. 


286 MID-TERTIARY CYTHERETIINAE 


The antero-dorsal lobe of the hinge of the left valve is swollen; the antero-ventral 
lobe is poorly developed; the antero-median tooth is prominent and downward 
pointing; the postero-median swelling is pronounced but small in comparison with 
the antero-median tooth; the posterior socket is circular rather than ovate. 

There are some 30 anterior pore canals, about 30 very closely packed posterior 
radial pore canals, and 15 ventral radial pore canals. The selvage is prominent; a 
flange groove is present, particularly prominent in the right valve, both anterior and 
posterior. Four spines come from the flange at the posterior and some g denticles 
are developed along an anterior fringe. A faint list is developed, particularly along 
the ventral side. 

The central muscle scars are in a slight pit; they are small, the two ventral scars 
close together, the third elongate, and the dorsal-most scar circular. 

Sexual dimorphism is pronounced; sex ratio 1-75. 


Discussion (I): Roemer (1838) originally described the species from the Tertiary 
of the Paris Basin; the specimen illustrated has six ridges and four or five posterior 
spines. Its shape is similar to the Lutetian forms of the species to be described 
below. Bosquet (1852) recorded it from the Sables inférieurs, Calcaire grossier, and 
the sables moyens; it was commonest in the Calcaire grossier. His diagram shows 
eight ridges and four spines. Keij (1957) redetermined Bosquet’s material and 
records several species and genera amongst it. Roemer’s material is thought to be 
lost and Keij’s revision of Bosquet’s material has been followed in the interpretation 
of the species. There is, therefore, still some doubt about the identity of Roemer’s 


MORPHOTYPES | suBsrecies 
SUB SPECIES 
A leilptly Ci | Dial Mee alee 
Co 
cumeneoutos [|= [|= [= [wo] = 
cratis 
A CS 


LOCALITY 


enue [=| | = [me eae faa 
woweites se) [se [v9 [77 [64/86] — | | erensoe 
covers ao) |esa|wo [s0 [isa] m0] - | 
seacncesnanca [wo | = [= [= [= [=f 
costellata 
pewwenven feo l= [= T= [=P [J 


Fic. 9. Morphotypes and subspecies of C. costellata (Roemer). 
The numbers in brackets refer to the number of specimens examined. 


OF NORTH-WEST EUROPE 287 


species. Bosquet (1852) mentions Roemer in his acknowledgments for supplying 
material however. Jones and Sherborn’s new variety C. costellata var. triangulata 
from the type Bracklesham Beds is a female dimorph. 

Amongst the material studied it is possible to recognize seven morphotypes which 
fall into four groupings, here recognized as subspecies. Three of these are chrono- 
logical subspecies and the fourth is geographical. (Text-fig. 9). For a discussion of 
the subspecies as used here see Sylvester-Bradley 1951. 


Morphotype A: 

The left valve, particularly of the female, is triangular with its apex at the ant- 
erior; the dorsal margin is gently convex with a prominent posterior hinge ear; the 
ventral margin is slightly convex, sweeping round at the posterior in a continuous 
curve to form the ventral part of the posterior margin; the dorsal part of the posterior 
margin turns sharply round to meet the hinge ear. The anterior margin is obliquely 
rounded. The right valve is much lower than the left with a strongly convex dorsal 
margin and a concave ventral margin. In dorsal view the carapace is ovate. 

The ornamentation between the ridges consists of a fine punctation. In the 
anterior part of the valve the ridges tend to become submerged within a large area 
of reticulation. A strong marginal rim runs around the anterior and dorsal margins. 
The sub-central plexus is simple. Ridge no. 6 is joined at both ends to no. 7 by a 
fine thread-like continuation. 

The outline of the inner margin differs slightly between the two valves. The 
anterior indentation is small and pointed; the anterior segment slopes down quite 
steeply to the small and ill-defined ventralindentation. In the left valve the median 
segment is at first level and then slopes upwards to the posterior segment, where the 
slope steepens markedly and sweeps up close to the dorsal margin; then it curves 
sharply downwards to form a deep and narrow posterior indentation. In the night 
valve the median segment is entirely level. In the males the posterior segment 
reaches much closer to the ventral margin. 


Morphotype B: 

Similar in most respects to Morphotype A. However, a very strong and character- 
istic sub-central plexus is developed, especially well seen in a specimen from Bam- 
brugge (Pl. 2, fig. 5). It consists of a raised platform between ridges 4 and 5 with 
three pits on its surface. This is a character developed in all the remaining mor- 
photypes and is generally very prominent. The shape is slightly different to Morpho- 
type A as the ventral margin is more convex and so the carapace appears to be much 
less triangular. 


Morphotype C: 

The shape of this and the remaining morphotypes is similar to that of Morphotype 
B but with the development of an anterior hinge ear in the left valve. 

The ornamentation between the ridges consists of a punctation intermediate in 
size between that of Morphotype A and that of Morphotype F. This and the 


288 MID-TERTIARY CYTHERETTINAE 


remaining morphotypes show a slight difference in ornamentation between the two 
valves. In the left valve ridge no. 6, joins No. 7 in the anterior but ends without 
joining either 5 or 7 at the posterior; in the right valve of some specimens ridge no. 7 
bifurcates near the posterior margin, the dorsal branch is joined by no. 5 and the 
ventral branch joins no. 8. There is a prominent sub-central plexus. The anterior 
area of reticulation is much reduced compared with Morphotypes A and B. 


Morphotype D: 


Large pits are developed between the longitudinal ridges, but can only be seen by 
straining. The pits are not developed in the posterior regions and cover a larger 
area of the valve in some specimens than in others. Other features are similar to 
Morphotype E. 


Morphotype E: 


This has a strong development of large pits between the ridges. The large pits 
are two abreast between the median portions of ridges no. 3 and 4, and in this respect 
Morphotype E differs from Morphotype F, which has a network of small pits. 
Ridges 5 and 7 join in the posterior, leaving an unattached no. 6 between them. 
The anterior area of reticulation is smaller than in Morphotype A, but larger than in 
Morphotype F. 


Morphotype F: 


The anterior margin is evenly rounded and in this respect differs from Morphotypes 
A-E. Pitting is developed between the ridges; the pits are large between ridges 
3-7, but form a network of small pits between 1, 2, and 3. The anterior area of 
reticulation is narrow, only two reticules wide; this results in the longitudinal ridges 
being more prominent in the anterior region than in Morphotypes A-E. The sub- 
central plexus is prominent. In the left valve ridge no. 5 is the strongest at the 
posterior and 6 and 7 join it; a few examples can be seen where no. 5 joins no. 7, and 
a few in which the ridges do not join at all. In the right valve no. 7 bifurcates near 
the posterior, the dorsal portion usually joining 5 and the ventral portion joining 8. 
This pattern is also present in a few left valves. 

The inner margin differs from that of Morphotypes A-E; the posterior segment is 
not so steep and does not reach so far towards the dorsal margin; the posterior 
indentation is therefore not so deep. 


Morphotype G: 


This is similar to Morphotype F except for the development of a smooth area at 
the anterior. This varies in extent ; in some specimens it is small, in others it extends 
almost to the sub-central plexus. Both males and females are affected. In the 
left valve ridge no. 5 is the most prominent at the posterior; no. 6 joins 5 or 7 or 
neither. The right valve is similar to that of Morphotype F. 


OF NORTH-WEST EUROPE 289 


Cytheretta costellata costellata (Roemer) 
(Pl. 2, fig. 1-10) 


1838 Cytherina costellata Roemer: 517, pl. 6, fig. 24. 

1852 Cythere costellata (Roemer); Bosquet: 58 (pars), pl. 2, fig. 11. 

1857 Cythere costellata (Roemer); Jones: 32, pl. 5, fig. 11. 

1874 Cythere costellata (Roemer); Brady, Crosskey and Robertson: 152, pl. 16, figs 13-15. 
1889 Cythere costellata (Roemer) var. tviangulata Jones and Sherborn: 30, pl. 1, fig. 21. 
1955 Cytheretta costellata (Roemer); Apostolescu: 26, pl. 5, figs 75, 76. 

1957 Cytheretta costellata (Roemer); Keij: 132, pl. 22, fig. 7. 

DiaGnosis: A subspecies of C. costellata with fine puncta between the ridges and 
usually with a simple sub-central plexus. 

MATERIAL: Material was examined from the following localities; Lutetian IV of 
Damery, Fisher Beds 21-24 of Selsey, the Keij Collection at Utrecht (Belgian 
Lutetian and Ledian), Ledian of Bambrugge. For numbers see Text-fig. 9. 
Io 3796-3803. 

TYPE LOCALITY AND HORIZON: Lutetian of the Paris Basin. 

STRATIGRAPHICAL RANGE AND DISTRIBUTION: See Text-fig. Io. 

DEscripPTion: This is composed of Morphotypes A, B, and C. It is small in size 
(see Text-fig. 1r and Discussion II). 

REMARKS: The Ledian specimens at Utrecht have not been included in Text-fig. 9 
because these were only measured and not divided into morphotypes. Most of them 
are Morphotype A; a few show very faint pitting in places and are therefore Mor- 
photype D. The specimens mentioned by Keij (1957; 133) as being reticulate 
are not C. costellata. 


Cytheretta costellata grandipora subsp. nov. 
(Pl. 3, figs 1-8) 


1852 Cythere costellata; Bosquet: 58 (pars). 
1957 Cytheretta costellata (Roemer); Keij: 132 (pars), pl. 6, fig. 9. 

DERIVATION OF NAME: Latin—grandis, large, and pora, pit; refers to the large pits 
developed between the ridges. 

D1acnosis: A subspecies of C. costellata characterized by the presence of large pits 
between the longitudinal ridges with a well developed sub-central plexus. 

HoLotyPeE: Io 3804, a female left valve. 

PARATYPES: Io 3805, 3806, 3808-9, 3811-13. 

MATERIAL: See Text-fig. 9. 

TYPE LOCALITY AND HORIZON: Carriere de Moiselles, Sables de Beauchamp. 

STRATIGRAPHICAL RANGE AND DISTRIBUTION: Sables d’Auvers, Auvers-sur-Oise ; 
Sables de Beauchamp, Moiselles; Sables de Cresnes, Le Ruel. All are in the Paris 
Basin. 


290 MID-TERTIARY CYTHERETTINAE 


DESCRIPTION: This consists of Morphotypes A-G, but principally A-E; thus there 
is a great range in ornamentation and size. For size, see Text-figs 9 and Io. 


Cytheretta costellata cratis subsp. nov. 
(Pl. 4, figs 1-8; Pl. 5, figs 1-3. Text-fig. 5) 
DERIVATION OF NAME: Latin—cratis, wickerwork; refers to the ornamentation. 


Diacnosis: A subspecies of C. costellata characterized by the development of pits 
between the ridges and a narrow area of reticulation at the anterior. 


HoLotyPe: Io 3814, a female left valve. 

PARATYPES: Io 3815-3822. 

MATERIAL: See Text-fig. 9. 

TYPE LOCALITY AND HORIZON: Verzy; Marnes a P. ludensis. 


STRATIGRAPHICAL RANGE AND DISTRIBUTION: Marnes a P. ludensis of Verzy and 
Chavencon in the Paris Basin. 


DEscRIPTION: This consists entirely of Morphotype F. For dimensions see Text- 
fig. Il. 


ENGLAND PARIS BASIN BELGIUM 


costellata antecalva costellata cratis 
MIDDLE & UPPER BARTON BEDS MARNES A P.ludensis 


costellata_grandipora 
SABLES MOYENS 


costellata costellata 
CALCAIRE GROSSIER 


UPPER BRACKLESHAM BEDS SABLES DE LEDE 


Fic. 10. Stratigraphical and geographical distribution of the subspecies of C. costellata 
(Roemer). 


OF NORTH-WEST EUROPE 291 


Cytheretta costellata antecalva subsp. nov. 
(Pl. 4, figs 9-11) 
1968 Cytheretta costellata (Roemer); Haskins: 165; Pl. 2, fig. 1-8. 


DERIVATION OF NAME: Latin—ante, anterior, and calvus, smooth; refers to the 
smooth anterior region. 


Diacnosis: A subspecies of C. costellata characterized by a smooth area at the 
anterior; pits are present between the longitudinal ridges. 


HototyPeE: Io 3823, a female left valve. 
PARATYPES: Io 3824-6. 


045 


Height 


e 
a 
(e@ 
\ 


© 


a 
7 \l 
iK 
b 


Aoi i 


040 


KEY 
o Bracklesham--—— 
@ Damery............ 
© Belgium —.—.—. ee 


0:35 
0-60 0-70 0-80 0-90mm 
Length ——— 


Fic. 11. Size distribution of C. costellata (Roemer). PVY=Verzy; PCC=Chavencon; 
PMS = Moiselles. 


292 MID-TERTIARY CYTHERETTINAE 


TYPE LOCALITY AND HORIZON: Barton; Upper Barton Beds, Bed H (Chama Bed). 


STRATIGRAPHICAL RANGE AND DISTRIBUTION: Middle and Upper Barton Beds, 
Barton; Middle Barton Beds, Alum Bay. 


DESCRIPTION: This consists of Morphotypes F and G, but mainly the latter. 
DIMENSIONS: Holotype, L=o-77 mm. 


REMARKS: Although the number of specimens is small, a further set of specimens 
was described by Haskins (1968) from Alum Bay which also had a smooth anterior 
region, so that this is apparently a well marked character. 


Discussion (II): Each assemblage studied shows a range of variation, indicated 
rather crudely by the proportion of morphotypes it contains. In fact gradations 
between morphotypes occur and the division into discrete groups is therefore 
arbitrary. The differences between subspecies are marked by changes in the 
proportion of the constituent morphotypes. Most of these changes can be cor- 
related with stratigraphical position, but in the case of C. costellata cratis subsp. nov. 
and C. costellata antecalva subsp. nov. it seems probable that we are dealing with 
contemporary subspecies that are geographically separated. The suggested relation- 
ships between the subspecies of C. costellata are shown in Text-fig. Io. 

In general there is an increase in size with time. This is clearly seen in Text-figs 
rr & 12. A comparison between the morphotypes found at Auvers and Moiselles 
(Text-fig. 12) shows that Morphotype A tends to be the smallest and E the largest. 


a ae eer a 


045+ 


0-40 S28 


Morphotypes 


0-65 070 0-75 0-80 0-85 0-90 


Fic. 12. Size distribution of morphotypes of C. costellata (Roemer) from Auvers-sur-Oise. 


OF NORTH-WEST EUROPE 293 


This is much clearer in the case of the females than the males. The species from 
Verzy are smaller than those from Chavengon; as these are of the same age, and 
because most other ostracods are similarly affected, this is thought to be ecologically 
controlled. The specimens from the Belgian Sable de Léde are much larger than 
those from Damery and Bracklesham. 

The ridge pattern remains remarkably constant, apart from the posterior involve- 
ment between ridges nos. 5,6and 7. With time there is an increase in complication 
of the ornamentation between the ridges and a decrease in the width of the anterior 
area of reticulation. At the posterior ridge no. 7 is at first the most prominent and 
no. 5 and 6 join it; this changes until no. 5 is the strongest and no. 6 and 7 join it 
(Text-fig. 13). 

The anterior margin changes from obliquely rounded to evenly rounded. The 
Ludian forms are proportionally higher than the Lutetian ones. 


6 See ei 
7 shila 


Fic. 13. Changes in ridges 5, 6 and 7 of C. costellata (Roemer). 


Cytheretta bambruggensis Keij 


(Pl. 3, fig. 9) 
1957 Cytheretta bambruggensis Keij: 131, pl. 6, fig. 10, pl. ro, figs 9-11. 


MATERIAL: One right valve from the Sables de Léde of Bambrugge. Io 3827. 
TYPE LOCALITY AND HORIZON: Bambrugge (Belgium) ; Sables de Lede. 


STRATIGRAPHICAL RANGE AND DISTRIBUTION: Lutetian, Ledian and basal Sables 
de Wemmel, Belgium; ‘Bartonian’ of the borehole at Delden, the Netherlands. 


Cytheretta crassivenia Apostolescu 
(Pl. 6, figs 2, 5) 


1852 Cythere costellata (non Roemer; pars); Bosquet: 58. 
1955 Cytheretta crassivenia Apostolescu: 261, pl. 5, figs 77-79. 
1957 Cytheretta cvassivenia Apostolescu; Keij: pl. 6, fig. 4; pl. 10, figs 12-14. 

MATERIAL: Two valves from the Lutetian of Grignon; nine valves and carapaces 
from the Lutetian of Damery; two carapaces from the type Sables d’Auvers; eleven 
valves and carapaces from the Sables de Beauchamp of Moiselles. Io 3828, 9. 


TYPE LOCALITY AND HORIZON: Montmirail; Lutetian. 


STRATIGRAPHICAL RANGE AND DISTRIBUTION: Lutetian, Sables d’Auvers of the 
type locality, Sables de Beauchamp of Moiselles in the Paris Basin; Sables de Léde 
of Belgium. 


294 MID-TERTIARY CYTHERETTINAE 


Discussion: Ridge no. 4 is strong and runs from the anterior to the posterior; 
beneath it are two short, but conspicuous ridges. In the specimens from Grignon 
and Damery (Lutetian) these two ridges do not quite join, the anterior one finishing 
just above the anterior end of the posterior ridge; in the specimens from Moiselles, 
however, they actually join. The reticulation between the ridges tends to be 
slightly stronger in the Moiselles specimens than in the Lutetian ones. 


Cytheretta decipiens Keij 
(Pl. 6, figs 8—r0) 


1955 Cytheretta concinna (non. Triebel) Apostolescu: 261, pl. 4, figs 72-74. 
1957 Cytheretta decipiens Keij: 133, pl. 6, fig. 8, pl. ro, figs 15-16. 


MATERIAL: One carapace from the type Sables d’Auvers, five valves and carapaces 
from the Sables de Beauchamp of Moiselles. Io 3830-32. 


TYPE LOCALITY AND HORIZON: Forest (Belgium), Cuisian. 


STRATIGRAPHICAL RANGE AND DISTRIBUTION: Cuisian, Lutetian and Ledian of 
Belgium; Lutetian, Sables d’Auvers, and Sables de Beauchamp of the Paris Basin. 


Discussion: It has been decided to retain this in the genus Cytheretta rather than 
Flexus because of the presence of several minor longitudinal ridges, apart from the 
three main ones. The ridge pattern is, in fact, very similar to that of C. crassivema 
and also to C. haimeana, C. scrobiculoplicata and C. bambruggensis. If Keij’s sup- 
position is correct, i.e. C. decipiens was the ancestor of Flexus concinnus (Triebel), at 
least some part of the genus Flexus has clearly been derived from Middle Eocene 
Cytheretta. The transition can be closely placed to the Bartonian. 


Cytheretta aff. decipiens Keij 
(Pl. 6, fig. 3) 

MATERIAL: One carapace from the Marnes a P. ludensis at Chavencon. Io 3833. 

Dimensions: L, 0-66; H, 0:34; L/H, 1-94. 

Discussion: This is clearly related to C. decipiens, but has lost most of the minor 
longitudinal ridges; there are still several ventral ridges however. This is probably 
the form called C. concinnus by Keij, but it differs from the latter in several respects. 
However, it could be placed in an evolutionary sequence, which, starting with 


C. decipiens, eventually gave rise to F. concinnus. As only one specimen was avail- 
able for study, this question has been left open. 


OF NORTH-WEST EUROPE 295 


Cytheretta haimeana (Bosquet) 
(Pl. 6, figs 1, 6) 


1852 Cythere haimeana Bosquet: 61, pl. 2, fig. 14. 

1852 Cytheve costellata (non. Roemer) Bosquet (pars): 58. 

1955 Cytheretta haimeana (Bosquet); Apostolescu: 262, pl. 5, figs 84-85. 
1957 Cytheretta haimeana (Bosquet); Keij: 136, pl. 6, fig. 7, pl. ro, figs 7, 8. 


MATERIAL: One valve from the Lutetian of Damery; ten valves and carapaces from 
the type Upper Bracklesham Beds; five valves and carapaces from the type Sables 
d’Auvers; eight valves and carapaces from the Sables de Beauchamp of Moiselles. 
Io 3834-5. 

TYPE LOCALITY AND HORIZON: Grignon; Lutetian IV. 


STRATIGRAPHICAL RANGE AND DISTRIBUTION: Cuisian and Lutetian of the Paris 
Basin (numerous localities) and the type Sables d’Auvers and Sables de Beauchamp 
of Moiselles; Upper Bracklesham Beds of England. 

Discussion: The specimens from Moiselles and Auvers are larger than those from 
Damery. The longitudinal ridges are more prominent because the cross ridges are 
not so strongly developed as in the Lutetian forms. 


Cytheretta ruelensis sp. nov. 
(Pl. 6, figs 4, 7; Pl. 5, figs 4-7) 


DERIVATION OF NAME: From the hamlet of Le Ruel. 


Diacnosis: A species of Cytheretta with 12 longitudinal ridges, of which no. 
4 and 5 are prominent, and with coarse puncta between the ridges. 


Hototype: Io 3837, a female left valve. 

PARATYPE: Io 3838. 

MATERIAL: Four carapaces and one left valve. 

TYPE LOCALITY AND HORIZON: Le Ruel; Sables de Cresnes. 


STRATIGRAPHICAL RANGE AND DISTRIBUTION: So far only known from the type 
locality. 


DESCRIPTION: Sexual dimorphism is very distinct, the males being more elongate. 
The left valve has an almost straight dorsal margin with a prominent posterior hinge 
ear. The anterior margin is obliquely rounded; the ventral margin is almost 
straight; the posterior margin is obliquely rounded. The right valve has a convex 
dorsal margin and a concave ventral margin. The carapace is narrowly ovate in 
dorsal view. 

The ornamentation consists of 12 longitudinal ridges with coarse puncta between 
them. Ridge no. 1 forms most of the dorsal margin, leaving it towards the anterior 
where it swings downwards to join a narrow anterior area of reticulation. Ridges 
2 and 3 are not strong ; towards the posterior no. 2 bifurcates and no. 3 joins the lower 
and stronger part. No. 4 and 5 are very strong running almost the whole length 


296 MID-TERTIARY CYTHERETTINAE 


of the carapace; a prominent gap is developed between them to the posterior of the 
sub-central plexus. The sub-central plexus is not very well developed and lies 
between ridges 4and5. There are four rows of coarse puncta between ridges 4 and 5 
forming two double rows; there are four more closely packed rows between 3 and 4; 
two between 2 and 3, and 5 and 6; and one between the remaining ridges. 


The internal features could not be clearly seen. 
DiIMENsIons (Carapace): 


i H L/H Ww 
Female 0:75 0°43 74 0°35 
Male 0°85 0°44 1-93 0°37 


Discussion: C. ruelensis shows a similarity to the C. haimeana group, but the 
ornamentation is quite distinct and unlike any of these in detail. The puncta 
between the ridges are unlike any other inter-costal ornamentation developed in this 
group. 

One specimen of a related form has been found in a sample from Moiselles (Pl. 7, 
fig. 11). The ridges form the same pattern as in C. ruelensis but they are all of about 
equal prominence. This is Cytheretta sp.A. 


Cytheretta eocaenica Keij 
(Plt, fig. 2} Pl..7, digs aro) 


1852 Cythere jurinei (non. von Munster); Bosquet: 56 (pars), pl. 2, fig. 9. 
1955 Cytheretta juvinei (non. von Munster); Apostolescu: 263, pl. 5, figs 86-89; pl. 6, figs go—-91. 
1957 Cytheretia eocaenica Keij: 134, pl. 6, fig. 6; pl. ro, figs 2-4. 


Diacnosis: (After Keij, 1957): ‘A species of the genus Cytheretta with the following 
characteristics; anterior margin obliquely rounded, obtusely angular ventrally; with 
horizontal rows of rounded depressions posteriorly; inner margin with three inward 
protrustions in the ventral half of the valve.’ 


MATERIAL: 109 valves and carapaces from the Sables de Lede of Bambrugge were 
available for study, donated by Dom. R. Rome, together with nine valves and 
carapaces from the Lutetian IV of Damery. Io 3839-44. 


TYPE LOCALITY AND HORIZON: Grignon; Lutetian IV. 


STRATIGRAPHICAL RANGE AND DISTRIBUTION: Cuisian and Lutetian of the Paris 
Basin; Lutetian and Ledian of Belgium; Upper Bracklesham Beds of England. 


Discussion: Keij describes the ornamentation as consisting of 3—5 horizontal rows 
of rounded depressions in the postero-ventral part of the valve with additional widely 
scattered depressions in the female. The specimens from Bambrugge have some 
nine rows of pits in the postero-ventral region and some five in the antero-ventral 
region. There is a smooth area near the centre of the valve representing the sub- 
central plexus from which run two prominent rows of pits towards the direction of 
the anteroventral angle. The Damery specimens fit Keij’s description with five 
postero-ventral rows of pits; the more ventrally placed pits, as developed at Bam- 


OF NORTH-WEST EUROPE 297 


brugge, are absent. However, the two prominent anterior rows can also be 
distinguished. 

Another feature of the Bambrugge sample is the presence of a few very large indi- 
viduals, about rin 8. These are similar in shape and ornamentation to the smaller 
specimens. The smaller individuals are definitely adults: the hinge, sexual dimor- 
phism, thick shell and inner margin are all well developed. This is probably an 
example of post-maturation moulting. 


DIMENSIONS: 
v H WwW L/H 
Female (normal) 0-78 0°47 0°40 1:66 
Female (large) 0:93 0°59 0-49 1°58 


Sex ratio: I : 3. 


Cytheretta oligocaenica sp. nov. 
(Pl. 8, figs 1-13) 
DERIVATION OF NAME: From Oligocene; refers to the strata in which it is found. 


Diacnosis: A species of Cytheretta with an obliquely rounded anterior margin and 
slightly convex ventral margin in the left valve; ornamentation consists of up to 8 
rows of pits in the postero-ventral region; there is often an ill-defined sulcus in the 
postero-lateral position. 


Ho.otyPe: Io 3845, a female left valve. 
PARATYPES: Io 3846-9. 


MATERIAL: Couches du Phare (Biarritz), 55 valves and carapaces; Couches de 
VAtalaye (Biarritz), 11 valves and carapaces; St. Geours de Maremne, 9 valves and 
carapaces; Blaignan, 5 carapaces. 


TYPE LOCALITY AND HORIZON: Biarritz; Couches du Phare (RO 271); Stampian. 


STRATIGRAPHICAL RANGE AND DISTRIBUTION: Couches de l’Atalaye and Couches 
du Phare, Biarritz; Faluns Bleues of St. Geours de Maremne; Argile a algues, 
Blaignan. 


DESCRIPTION: Sexual dimorphism is distinct. Sex ratio, 1: 3. The left valve has a 
prominent posterior hinge-ear and a convex dorsal margin; the anterior margin is 
obliquely rounded; the ventral margin is slightly convex; the posterior margin is 
obliquely rounded. The greatest height is just to the anterior of centre. The right 
valve has its greatest height about one quarter of the way from the posterior margin 
and this results in a slight triangular shape as the almost straight dorsal margin 
slopes towards the anterior margin; the ventral margin is concave. 

The ornamentation consists of up to 8 rows of pits in the postero-ventral region. 
An ill-defined sulcus is often present in the postero-lateral position. 

The antero-dorsal lobe of the hinge of the left valve is swollen; the antero-ventral 
lobe is large and prominent; the antero-median tooth is large; the postero-median 


298 MID-TERTIARY CYTHERETTINAE 


swelling is prominent. The anterior tooth of the right valve is crescentic-shaped in 
lateral view; in dorsal view both teeth of the right valve are large and squat (Plate 
8, Fig. 8-13). 

The inner margin has a narrow anterior indentation and small ventral and posterior 
indentations; the anterior segment is semi-circular; the median segment is long with 
a gentle upward slope; the posterior segment is short and semi-circular. There are 
some 35 anterior and 17 ventral radial pore canals. The posterior radial pore canals 
are very closely packed and there are about 80 of them; they are not divisible into 
two groups. The selvage is very close to the anterior margin; there is a small 
posterior flange groove and a larger ventral one; a weak list is present. 

As with C. eocaenica, there are a few very large individuals, about 10%. 


DIMENSIONS: 


L H Ww L/H 
Female 0°85 0:53 0:51 I-60 
Male 0-86 0°49 0-41 I-71 
Large form, male 0-98 0:58 _- 1:70 


Discussion: This is very similar to C. eocaenica Keij. It differs in shape; the 
antero-ventral angle is rounded and not angular as in C. eocaenica, the ventral 
margin is slightly convex, not straight, and the greatest height is just to the anterior 
of centre, whereas it is about one third of the way from the anterior in C. eocaenica. 
The right valve is much higher in the posterior in C. oligocaenica. There are more 
anterior radial pore canals in the latter, 35 compared with 27-30. The inner margin 
is similar in both species, and in this respect they differ from C. juvinez (von Munster), 
which has a very large and circular posterior indentation. 

See also C. geoursensis sp. nov. 


Cytheretta geoursensis sp. nov. 
(Pl. ro, figs I, 3, 5) 


DERIVATION OF NAME: From St. Geours de Maremne. 


Diacnosis: A large species of Cytheretta with a prominent posterior hinge ear, 
convex ventral margin of left valve, and a finely punctate outer surface. 


Ho.otyPe: Io 3850, a female left valve. 
PARATYPES: lo 3851-2. 
MATERIAL: Eight valves and carapaces. 


TYPE LOCALITY AND HORIZON: Marniére d’Escornbéou, near St. Geours de Maremne 
(Aquitaine Basin); Faluns bleues, Oligocene(?) (Chattian?). 


STRATIGRAPHICAL RANGE AND DISTRIBUTION: So far only known from the type 
locality. 


DESCRIPTION: Sexual dimorphism is distinct; sex ratio, 1:3. The left valve has 
a very prominent posterior hinge ear; the dorsal margin is strongly convex; the 
anterior margin is obliquely rounded; the ventral margin is strongly convex, par- 


OF NORTH-WEST EUROPE 299 


ticularly towards the posterior; the posterior margin is obliquely rounded. The right 
valve has a slightly convex dorsal margin and a slightly concave ventral margin. 

The whole outer surface of the carapace is covered with a very superficial appearing 
punctation. Two or three rows of pits in the postero-lateral position can be seen on 
some specimens, and one right valve has these quite prominently developed. 

The hinge, inner margin, selvage and list are as for C. oligocaenica. There are 27 
anterior radial pore canals, but the exact number of posterior radial pore canals 
could not be determined. 


DIMENSIONS: 
1B H Ww L/H 
Female 0:98 0:58 0-60 1:69 
Male 1:07 0:58 0:50 1:84 


Discussion: This could perhaps be regarded as a post-maturation moult stage of 
C. oligocaenica sp. nov. similar to those already described. However, unlike these, 
this is not merely a larger version of the small forms. It differs from C. oligocaenica 
in shape, particularly the strongly convex ventral margin of the left valve; in 
ornamentation; and in the number of anterior radial pore canals (27 compared 
with 35). 


Cytheretta carita sp. nov. 
(Rito; tigs|5, S)o—11: Plivno, fig. 7: Lext-fig> 14) 


DERIVATION OF NAME: Latin—carita, to be without or to be deprived; refers to 
the lack of ornamentation. 


Diacnosis: A smooth species of Cytheretta with an obliquely rounded anterior 
margin and two ‘dimples’ in the posterior. 


HototyPe: Io 3853, a female left valve. 
PARATYPES: Io 3854-8. 


MATERIAL: 39 valves and carapaces from the type Auversian; 57 from Moiselles; 
5 from Le Ruel, Sables de Cresnes; 1 from the Marnes a P. ludensis at Verzy. 


TYPE LOCALITY AND HORIZON: Carriere de Moiselles; Sables de Beauchamp. 
STRATIGRAPHICAL RANGE AND DISTRIBUTION: ‘Bartonian’ of the Paris Basin. 


DESCRIPTION: Sexual dimorphism distinct; sex ratio, 1 : 2°5._ The dorsal margin 
of the left valve has a prominent posterior hinge ear, is straight until about the mid- 
point when it slopes down to the anterior margin, which is very obliquely rounded. 
The ventral margin is slightly convex and curves into the posterior margin, which is 
rounded. The dorsal margin of the right valve is more irregular; a slight hinge ear 
is present at the posterior and the anterior tooth projects beyond the margin. There 
is a marked concavity between the hinge ear and the posterior margin. The ventral 
margin is slightly concave. In dorsal view it is ovate. 

The valve issmooth. At the posterior are two dimples, one in the postero-ventral 
angle and the other higher along the posterior margin. 


300 MID-TERTIARY CYTHERETTINAE 


In the hinge of the left valve, the antero-ventral lobe is weakly developed, leaving 
the anterior socket almost open ventrally; the antero-dorsal lobe is flat to lobate and 
small; the antero-median tooth is large; the postero-median swelling small. In the 
right valve the anterior tooth is large and the posterior tooth is slightly reniform. 

The anterior indentation of the inner margin is narrow; the ventral deep and 
prominent; and the posterior broad, but deep. The median segment is almost flat; 
the posterior segment is steeper, but not very pronounced. The muscle scars are 
normal, the two ventral scars being close together. They are situated in a slight pit. 

The selvage runs along the anterior margin of both valves, so there is no anterior 
flange groove. A ventral flange groove is well developed, as well as a small posterior 
one. A very weak list is present along the ventral and posterior duplicature. 


Fic. 14. Cytheretta cavita sp. nov.; female right valve; x75. 


DIMENSIONS: 
1 H WwW L/H 
Female 0:87 0°55 0°43 1°58 
Male 0:93 0°53 0-41 I-75 


Discussion: This differs from other smooth Cytheretta species such as C. rhenana 
Triebel by its shape and the presence of the posterior dimples. It shows a very close 
relationship to C. eocaenica, but lacks the longitudinal rows of pits of the latter. 


Cytheretta cellulosa sp. nov. 
(Pl. 9, figs 1-4, 6, 7) 
DERIVATION OF NAME: Latin—cellulosus, full of little cells, referring to the orna- 
mentation. 


DraGnosis: A species of Cytheretta with 13 rows ot pits which converge at the 
posterior; dorsal area is smooth. 


HoLotyPeE: Io 3859, a female left valve. 
PARATYPES: Io 3860-63. 


MATERIAL: Eight valves and carapaces from the type Auversian; fourteen valves 
and carapaces from Moiselles. 


OF NORTH-WEST EUROPE 301 


TYPE LOCALITY AND HORIZON: Auvers-sur-Oise; Sables d’Auvers. 
STRATIGRAPHICAL RANGE AND DISTRIBUTION: Auversian of the Paris Basin. 


DESCRIPTION: Sexual dimorphism is pronounced; sex ratio, 1: 3. The dorsal 
margin of the left valve has a prominent posterior hinge ear and is convex. The 
anterior margin is slightly obliquely rounded; the ventral margin is straight in the 
central portion; the posterior margin is very obliquely rounded. In the male, the 
ventral margin has a very straight appearance. The right valve has a concave 
ventral margin. Carapace is ovate in dorsal view. 

The ornamentation of the left valve consists of 13 rows of small pits. In the 
posterior region these rows converge and merge into one another; the pitting is very 
fine. In the central region the rows are distinct and consist of a single line of pits 
larger in the centro-dorsal region. The central rows converge upon an ill-defined 
sub-central plexus, which is almost smooth. To the anterior of this the rows consist 
of double rows of puncta; there are five of these, together with three ventral rows of 
single puncta which are continuous along the ventral region. The dorsal area is 
smooth. The right valve is similar except that there are single rows of pits in the 
anterior region. 

The hinge of the left valve has a swollen antero-dorsal lobe; a small antero-ventral 
lobe so that the anterior socket is virtually open ventrally, as is the posterior socket ; 
a large antero-median tooth; and a small inconspicuous postero-median swelling. 
The anterior tooth of the right valve is large, and the posterior tooth is prominent. 

The inner margin could not be clearly seen. There are some 20 anterior radial 
pore canals. The central muscle scars are in a slight pit, and the two ventral ones 
are close together. One very prominent dorsal muscle scar can be seen above the 
fulcral point. The selvage runs close to the anterior margin; there is a ventral 
flange groove and a small posterior one. A weak list is present along the anterior, 
ventral and posterior parts of the duplicature. 


DIMENSIONS: 
Ly H Ww L/H 
Female 0:80 0:49 0:38 1-65 
Male 0°93 0-51 0°43 1:82 


Discussion: C. cellulosa bears a ressemblance to C. tenuipunctata (Bosquet), but 
the pattern of pits is different and the outline of the valve is completely different. 
C. eocaenica Keij from the Ledian of Bambrugge often develops pits over a large 
area, although never to the same extent ashere. The shape, however, is similar, and 
it is thought likely that C. eocaenica is the ancestor of C. cellulosa, with such forms as 
those from Bambrugge as intermediates. 


Cytheretta aff. cellulosa 
1968 Cytheretta minor (non Lienenklaus) Haskins: 167, pl. 1, figs 30-35. 


Discussion: Haskins records this from the Barton Beds in Alum Bay. In many 
respects it appears to be intermediary between C. cellulosa and C. minor. 


302 MID-TERTIARY CYTHERETTINAE 


Superspecies Cytheretta laticosta (Reuss) 


DiaGnosis: A group of species of the genus Cytheretta characterized by three longi- 
tudinal ridges. The dorsal ridge is convolute; the median ridge contains four 
depressions along its ventral side; the ventral ridge is the most prominent of a group 
of ridges developed in the ventral part of the valve. 


DESCRIPTION: The carapace generally has a massive appearance with a thick shell; 
it is strongly inequivalve, and sexual dimorphism is pronounced. In the left valve 
there is a prominent posterior hinge ear. In the right valve the anterior tooth 
projects beyond the margin and the ventral margin is concave. In dorsal view the 
carapace is swollen posteriorly in both males and females, but this is more pronounced 
in the latter. 

The ornamentation consists predominantly of three thick longitudinal ridges. 
The dorsal ridge runs along the margin, but does not reach the anterior margin; the 
median ridge swells in the central region and contains four depressions on its ventral 
side, each of which has a normal pore canal opening into it. This runs from the 
anterior margin to the posterior, where it curves upwards to form a margin to the 
hinge ear. The ventral ridge also contains four depressions with normal pore canals, 
much better seen in the right valve. In the left valve this ridge is really the most 
pronounced of a series of ventral ridges, of which there are seven in all. In the right 
valve the lower ventral ridges are indistinct or absent, and this gives the whole 
valve a strongly tri-costate appearance. A prominent marginal rim runs around the 
anterior margin and the anterior portion of the ventral margin. In the right valve 
there is a posterior marginal rim. There are some eight marginal antero-ventral 
denticles, each of which bears a radial pore canal, and three posterior ones. The 
latter are larger in the right valve. The whole surface is finely punctate, although 
this can only be seen on well preserved specimens. 

The hinge of the left valve has a swollen, knob-like, antero-dorsal lobe; the antero- 
ventral lobe is small; the antero-median tooth is prominent ; postero-median swelling 
is small. In the right valve the anterior tooth is large and the posterior tooth circular 
in plan. 

The selvage is prominent, particularly in the right valve; there is a well developed 
flange groove in the anterior, ventral, and posterior; and a list is present in the 
postero-veatral region. There are some 32 anterior radial pore canals, 20 ventral, 
and 18 posterior; and 29 normal pore canals which are arranged in sympathy with 
the ornamentation (Text Fig. 15). The central and dorsal muscle scars are as for the 
genus. 


Cytheretta laticosta (Reuss) 
(Pl. 2, fig3; Plo xo, figs?2) 4, 6).8, 93. Pl. a2) figs 1—2 55 Lext-tig. 15): 


1850 Cypridina laticosta Reuss: 87, pl. 11, fig. 13. 

1857 Cythere plicata var. laticosta (Reuss); Jones: 32, pl. 5, fig. 8 (pars). 
1889 Cytheve plicta var. laticosta (Reuss); Jones and Sherborn: 29 (pars). 
1957 Cytheretta laticosta (Reuss); Keij: 137, pl. 18, figs 15-18; pl. 21, fig. 16. 
1968 Cytheretta laticosta (Reuss) ; Haskins: 166 (pars), pl. 2, figs 23, 27, 28. 


OF NORTH-WEST EUROPE 303 


Dracnosis: A member of the superspecies C. laticosta with an evenly rounded 
anterior margin, convolute dorsal ridge and small areas of coarse puncta around the 
median and ventral ridges. 


MATERIAL: Three carapaces from the Lower Barton Beds of Alum Bay; numerous 
specimens from the Middle and Upper Barton Beds of Barton, and Alum Bay; 
fifteen valves and carapaces from the Marnes a P. ludensis of Verzy, and five from 
Chavengon. Io 3864-70. 


TYPE LOCALITY AND HORIZON: Barton Clay of Barton (see discussion). 


STRATIGRAPHICAL RANGE AND DISTRIBUTION: Barton Clay of Barton, Alum Bay 
and Whitecliff Bay; Marnes a P. ludensis of Verzy and Chavencon; Argile d’Asche 
of Oedelem (Belgium). 


DESCRIPTION: Sex ratio, I : 1:6. The carapace is massive, the shell is thick. The 
dorsal ridge is thick with convolutions forming some six depressions, which bear 
normal pore canals. The median ridge has a prominent swelling in the central part 
and has an area of coarse puncta around the four depressions. The ventral ridge 
likewise has an area of coarse puncta. 

The inner margin has a narrow and deep anterior indentation, particularly in the 
right valve, and a prominent ventral one. The anterior segment is sharply rounded. 
The median and posterior segments are inseparable; they slope up to the posterior 
indentation, which is quite close to the ventral margin. 

DIMENSIONS: 


Left valve Right valve 
IL H L/H WwW 1 H L/H 


Female o-80 + 0:02 0:50+0-01 1I:60+0-04 0:46 0-79 0:42 1:88 
Male 0:86 + 0:02 0-49 + 0:01 1:76 +0:04 0:45 0:89 0:46 1:94 
Discussion: Reuss described this as coming from the London Clay of Barton, 
Hampshire. This relates to the idea prevalent in the early 19th century that the 
clay at Barton was of the same age as that at London; in fact, the London Clay is 
Lower Eocene, while the Barton Clay is Upper Eocene. 


Fic. 15. Cytheretta laticosta (Reuss) showing distribution of normal pore canals in 
relationship to ornamentation; 75. 


304 MID-TERTIARY CYTHERETTINAE 


Cytheretta forticosta sp. nov. 
(Pl. 11, figs 1-4, 8, 9; Pl. 12, figs 6-12) 


1857 Cythere plicata (non. von Munster); Jones: 32 (pars). 
1968 Cytheretta laticosta (Reuss); Haskins: 166 (pars), pl. 2, figs 19-22, 24-26, 29. 


DERIVATION OF NAME: Latin—fortis, strong; costa, ridge. Refers to the three 
strong longitudinal ridges. 


DraGnosis: A member of the superspecies C. Jaticosta with an obliquely rounded 
anterior margin and simple median ridge. 


HoLotyPeE: Io 3871, a female left valve. 

PARATYPES: Io 3872-8. 

MATERIAL: Numerous specimens from the localities mentioned below. 

TYPE LOCALITY AND HORIZON: Fisher Beds 17-18, Upper Bracklesham Beds, 
Whitecliff Bay. 

STRATIGRAPHICAL RANGE AND DISTRIBUTION: Upper Bracklesham Beds of White- 
cliff Bay, Selsey Bill, and Bramshaw (New Forest) ; Sables de Cresnes, Le Ruel. 


DESCRIPTION: Sex ratio, I : 2:5. The carapace is massive. The left valve of the 
female has a circular outline; the dorsal margin is strongly convex; the anterior 
margin is obliquely rounded; the ventral margin is short and straight; the posterior 
margin is very obliquely rounded. In the right valve the dorsal outline is irregular, 
and the ventral margin is concave. 

The dorsal ridge has five depressions, each of which bears a normal pore canal. 
The four pits on the median ridge are simple; those on the ventral ridge are prominent 
in both valves. The surface of the valveis punctate. In the right valve the ventral 
group of ridges are distinct in the anterior and posterior regions. 

The inner margin is similar to that of C. laticosta except that the joint median and 
posterior segments have two undulations. 

DIMENSIONS: 


Left valve Right valve 
IL, H L/H W L H L/H 


Female 0:77 40:03 0°52 0:02 1:'46+0:04 0°52 0:83 0-45 1°84 
Male 0:87 + 0:03 0°54 40:02 1:62 +0:05 0:52 0-90 0-48 1:88 


Cytheretta porosacosta sp. nov. 
(Pl. 11, figs 5-7; Pl. 12, figs 3, 4) 


1857 Cythere plicata (non. von. Munster); Jones: 32 (pars), pl. 4, fig. 16; pl. 5, fig. 8. 
1889 Cytheve plicata (non. von Munster); Jones and Sherborn: 29 (pars), pl. 1, fig. 18. 
1968 Cytheretta laticosta (Reuss); Haskins: p. 166 (pars). 


DERIVATION OF NAME: Latin—porosus, full of holes; costa, ridge. Refers to the 
heavily punctate ornamentation. 


Diacnosis: A member of the superspecies C. lJaticosta with an evenly rounded 
anterior margin, simple ridge, and wide areas of large puncta. 


OF NORTH-WEST EUROPE 305 


Ho.otyPe: Io 3879, a female left valve. 
PARATYPES: Io 3880-83. 
MATERIAL: Numerous valves from the localities mentioned below. 


TYPE LOCALITY AND HORIZON: Colwell Bay, Isle of Wight; Middle Headon Venus 
Bed. 

STRATIGRAPHICAL RANGE AND DISTRIBUTION: Brockenhurst Beds of Brockenhurst 
and Whitecliff Bay; Middle Headon Beds of Colwell Bay, Headon Hill, Whitecliff 
Bay, Milford, and Brockenhurst. 


Description: The dorsal margin of the left valve is slightly irregular due to the 
over-reach of the dorsal ridge; otherwise it is straight to slightly convex. The 
anterior margin is evenly rounded; the ventral margin is slightly concave; and the 
posterior margin obliquely rounded. 

In the left valve the dorsal ridge has several faint depressions, but is fairly simple. 
The median ridge is narrow, with four very faint depressions on the ventral side. 
There is no strong ventral ridge. In the right valve however, the ventral ridge is 
distinct due to the absence of the lower ventral ridges. Large areas of coarse puncta 
are developed amongst the ventral group of ridges and around the median ridge. 


DIMENSIONS: 
Left valve Right valve 
i H L/H I H L/H 
Female 0-74+0:02 0-44+0-01 1:68-+0-:025 0:74 0:38 1:92 
Male 0-78-+0-:02 0-42+0-:01 1:84+0:04 0:82 0:40 2:05 


Discussion: The three species described are only part of the superspecies 
C. laticosta. Other forms not studied are found in the London Clay of the London 
and Hampshire basins and the Lower and Middle Bracklesham Beds. 

The most noticeable difference between these species is the shape of the carapace. 
This is most marked in the female dimorph. The species represent three quite 
distinct groups (Text-fig. 16). The L/H ratio is: 


Female Male 
C. forticosta 1:46-0:04 1:62-0:05 
C. laticosta I-60-L0:03 1:76-0:04 
C. porosacosta 1-68-+L0:025 1:84-+0-04 


The anterior margin changes from obliquely rounded in C. forticosta to evenly 
rounded in C. laticosta and C. porosacosta. 

The three longitudinal ridges are more complex in C. laticosta. The dorsal ridge is 
convolute and complicated. The four depressions in the median ridge are prominent 
and punctate; in C. forticosta there are only four large puncta and no depressions; in 
C. porosacosta the depressions are almost absent. The ventral ridge has a prominent 
central area with coarse puncta; these are not present in C. forticosta, while in 
C. porosacosta the puncta cover a large area of the valve. In the right valve of 
C. forticosta the ventral group of ridges are stronger than in C. laticosta and 
C. porosacosta. 


306 MID-TERTIARY CYTHERETTINAE 


The trends seen in these three species are, therefore: 

(i) Change from a rounded to a more elongate shape. 

(ii) Anterior margin from obliquely rounded to evenly rounded. 

(11) Development of coarse puncta, especially around the median and ventral 
ridges. 

The group of specimens from Le Ruel have a mean L/H ratio of 1-43 and have a 
more rounded appearance than the English C. forticosta. The specimens from Selsey 
Bill and Bramshaw are more elongate, with a mean ratio of I-50. The Whitecliff 


0:60 


o 
* Bramshaw 

e@ Selsey Bill 

© Whitecliff Bay 

x Barton 

© Ludian, Paris Basin 
+ 


Standard 
deviation 


Headon Beds 


J 
a 
a) 


Height - mm—— 


0-65 0-70 0-75 0:80 0-85 
Length -mm—_ > 


Fic. 16. Size distribution of species of the superspecies C. laticosta (Ruess). 


OF NORTH-WEST EUROPE 307 


Bay specimens have a mean of 1-46 and have an even distribution. There is con- 
siderable overlap between these specimens, however, which does not occur between 
these specimens of C. laticosta and C. porosacosta. 

The variation in size is most noticeable between C. porosacosta on the one hand and 
C. laticosta and C. forticosta on the other. This is thought to be environmental 
because C. porosacosta is found in beds with a mixed marine and brackish water 
fauna. The thinner shell of C. porvosacosta and the general weakness of the three 
ridges is probably also connected with this. The specimens of C. forticosta from 
Bramshaw and Selsey are seen to be smaller than those from Whitecliff Bay; and 
C. laticosta from the Ludian of the Paris Basin are smaller than those from the 
Barton Clay. This may be environmental. The specimens from Le Ruel show a 
large range in size, due perhaps to the nature of the Sables de Cresnes, which are 
coarse-grained current-bedded sands, often with rolled macro-fossils. 

Eventually, specimens of an intermediate nature may be found between these 
three species, in which case they will become subspecies. It is thought highly likely 
that such intermediates exist, but at the moment there are present three distinct 
groups with no overlap. 


Superspecies Cytheretta tenuipunctata (Bosquet) 


The superspecies C. tenuipunctata comprises a group of ostracods with similarities 
in shape of lateral view, ornamentation, and internal structures. The following 
species and subspecies are included: 


. tenuipunctata tenuipunctata (Bosquet) 
. tenuipunctata absoluta subsp. nov. 
. tenuipunctata livata subsp. nov. 
. tenuistriata tenuistriata (Reuss) 
. tenuistriata ornata subsp. nov. 
. bernensis Oertli 
. buttensis sp. nov. buttensis subsp. nov. 
. buttensis reticulata subsp. nov. 
. mintpunctata sp. nov. 
The following are tentatively included: 
C. triebeli Oertli 
C. variabilis Oertli 
C. ramosa ramosa (Lienenklaus) 
C. vamosa sublaevis Triebel 


MAA A AAA AO 


There are further groups of ostracods from the Oligocene of western Europe which 
are also closely related to the superspecies. These are discussed below. 


Dracnosis: A superspecies of the genus Cytheretta with up to 13 longitudinal ridges, 
often stronger in the ventral half of the valve, which form a regular pattern, although 
differing slightly in detail between species. There are three ridges in the anterior 
part which run from the region of the sub-central plexus towards the antero-ventral 
angle. In lateral view the carapace is elongate with pronounced sexual dimorphism ; 
D 


308 MID-TERTIARY CYTHERETTINAE 


in dorsal view it is ovate or tapered towards the anterior. The valves are not 
strongly inequivalve. 


DESCRIPTION: The shape varies, but in general it is elongate in lateral view. In 
dorsal view it is usually ovate, or slightly triangular with its apex at the anterior. 
Sexual dimorphism is pronounced; sex ratio, 1 : 2. The valves are inequivalve, but 
not strongly so. 

Up to 13 longitudinal ridges are developed, which may be strong or weak. In 
some species no ridges are present in the dorsal half of the valve. The ornamentation 
between the ridges varies from species to species. A complete development is seen 
in Text-fig. 17. 

Ridge no. I runs from near the posterior hinge ear, disappearing to the anterior of 
the sub-central plexus. No. 2 is often formed of a series of short curved ridges, 
usually broken and bifurcating. No. 3 joins no. 2 in the posterior, runs above the 
sub-central plexus, and just to the anterior of it joins no. a. In some species, and 
particularly in the right valve, ridge a is very prominent, sloping sharply towards the 
antero-ventral angle. The sub-central plexus is an irregular, smooth area, varying 
from species to species, but usually prominent. Three parallel ridges, a, b, and c, 
run from the sub-central plexus towards the antero-ventral angle; these are diag- 
nostic of the superspecies. There are another three parallel ridges, 4, 5, and 6 to the 
posterior of the sub-central plexus. Ridge no. 7 joins no. 4 at the posterior and no. 8 
at the anterior. Ridges 8-13 are approximately parallel to the ventral margin. 
The ridges form a complicated pattern at the posterior, seen in Text-fig. 17. Ridges 
9-13 disappear amongst fine puncta at the posterior. 

The antero-dorsal lobe of the hinge of the left valve is prominent and slightly 
swollen; the antero-ventral lobe is prominent; the antero-median tooth is well 
developed, but the postero-median swelling is virtually absent. In the nght valve 
the anterior tooth is slightly reniform in shape; in dorsal view the two teeth appear 
to be almost equal in size. 

The selvage is prominent along the ventral and posterior margins. A wide flange 
groove with a well marked flange is present in the ventral region; in the posterior 
the flange groove is narrow and a small fringe is developed. Along the anterior 


enki br 


Fic. 17. Ridges of the superspecies Cytheretta tenuipunctata (Bosquet). The specimen is 
C. tenuistrviata oynata subsp. nov; X75. 


OF NORTH-WEST EUROPE 309 


margin a few very small denticles are present; a radial pore canal opens from each 
of them. There are some 35 anterior radial pore canals and some 40 closely spaced 
posterior pore canals. The inner margin varies slightly from species to species. 


Cytheretta tenuipunctata (Bosquet) 


Diaenosis: A species of the superspecies C. tenuipunctata with a prominent sub- 
central plexus and a medium to coarse pitting between the ridges, the pits often being 
in double rows in the median part of the valve. The ridges are strongly developed. 


Discussion: This was described by Bosquet from the Argile a N. comta of Belgium. 
It is very similar to C. tenwistriata (Reuss), and Keij (1957) believed that the two 
were synonymous. This was because of the similarities in ornamentation. The 
two species are here regarded as distinct, but are placed within the same superspecies. 
C. tenumstriata is a much larger ostracod than C. tenuipunctata, but in itself this need 
not be important. In the Paris Basin however, the two co-exist without inter- 
mediaries, so that the difference in size is very obvious; thus they formed two 
separate populations which must be assumed to be specifically distinct. The 
ornamentation between the ridges consists of a coarser pitting in C. tenuipunctata 
than in C. tenuistriata. 


Cytheretta tenuipunctata tenuipunctata (Bosquet) 


1852 Cythere jurvinei (non. von Munster); Bosquet: 56 (pars). 
1852 Cythevre jurinet var. tenuipunctata Bosquet: 56, pl. 2, fig. ro. 
1957 Cytheretta tenuipunctata (Bosquet); Keij: 138, pl. 5, fig. 21; pl. 6, fig. 5. 
TYPE LOCALITY AND HORIZON: Berg, near-Kleine Spouwen, Belgium; Argile a 
N. comta (Rupelian). 


STRATIGRAPHICAL RANGE AND DISTRIBUTION: Upper Tongrian (?) and Lower 
Rupelian of Belgium. 


Dimensions: (After Keij): 


Lectotype (Male R) 0:96 x 0:47 
Female L 0°88 x 0-51 


Discussion: Keij (1957) has selected a lectotype and redescribed species as having 
6-8 ridges which gradually vanish towards the anterior and posterior margins; 
between the ridges are fine pits, mostly in two rows; towards the dorsal margin the 
surface is pitted, but without ridges; the areas along the anterior, posterior, and 
dorsal margins are smooth; and a sub-central plexus is well developed. 

C. tenuipunctata tenuipunctata differs from the two subspecies described below by 
the absence of the dorsal ridges. 


310 MID-TERTIARY CYTHERETTINAE 


Cytheretta tenuipunctata absoluta subsp. nov. 
Pl. 14, figs 1-4, 6, 7; Text-fig. 18) 


DERIVATION OF NAME: Latin—absolutus, complete; refers to the ornamentation 
which completely covers the valve, unlike C. tenwipunctata tenuipunctata. 


DiacGnosis: A subspecies of C. tenuipunctata in which the full 13 ridges of the 
superspecies C. tenuipunctata are developed; the ornamentation between the ridges 
consists of a fine pitting, in double rows in the median and dorsal parts of the valve, 
and single rows between the ventral ridges. 


Ho.otyPeE: Io 3884, a female left valve. 

PARATYPES: Io 3885-9. 

MATERIAL: 55 adult valves and carapaces and 68 larval stages from Cormeilles. 
TYPE LOCALITY AND HORIZON: Cormeilles-en-Parisis; Marnes a Huitres. 
STRATIGRAPHICAL RANGE AND DISTRIBUTION: Marnes a Huitres of the Paris Basin. 


DescripTION: The dorsal and ventral margins of the valves are sub-parallel, 
particularly in the left valve. In the latter there is a prominent posterior hinge 
ear; the dorsal margin is slightly convex; the anterior margin is evenly rounded; the 
ventral margin is straight or slightly concave ; the posterior margin obliquely rounded 
In the right valve the ventral margin is concave and there is a concavity in the 
postero-dorsal position. In dorsal view the carapace is ovate. 

The ridges are well defined, particularly in the right valve. The ornamentation 
between the ridges consists of a fine pitting. Between ridges I, 2, 3 and 4, 6and7, 
a, b, c, there is a double row of pits; between the ventral ridges there is a single row. 
The anterior region is reticulate. 

The inner margin (Text-fig. 18) has a broad anterior and posterior indentation and 
a well marked ventral indentation. The anterior segment is rounded, and the joint 
median and posterior segments are undulating. 

Two larval stages have been recognised (Text-fig. 19). In these the complete 
ridge pattern of the adult is developed with small puncta between them; these are in 
rows of three between ridges no. 6 and 7, and in double rows between the others. 
Ridges 8 and 9 are very strong in the posterior region and in larval stage 7 there is a 
distinct swelling in this region. 

DIMENSIONS: 

Left valve Right valve 
IU, H L/H W L H L/H 
Female 0°87 + 0:03 0-49 + 0-01 1:76+ 0:05 0:43 0:87 0:46 1-89 
Male I-00 + 0:02 O51 + 0°01 1:96 + 0:02 0:43 0:98 0:50 1:96 

Discussion: This subspecies differs from C. tenuipunctata tenuipunctata in the 
larger number of ridges, caused by their presence in the dorsal regions. It differs 
from C. tenuipunctata lirata subsp. nov. in having a slightly different shaped dorsal 
margin, the latter having a weak anterior hinge ear in the left valve, and in the 
ornamentation between the ridges which show a great deal of variation in 
C. tenuipunctata livata. 


OF NORTH-WEST EUROPE 311 


Fic. 18. Cytheretta tenuipunctata (Bosquet) absoluta subsp. nov.; female right valve; x75. 


0:60 


@ Expected size, after the 
method of Anderson 


(1964) 


0:50 ° © 00f Oo 
[orole} ° ° 
x 828 
te Oe) 
E 
E 
£ © xox 
cy x x t x x 
z= >» Bee ko Xo 
Ox x 
040 XM EKIN, x x 
me 8(33) 
° 
x @ o 
x 
* 766) 
x 
030 x n 1 1 1 
0:50 060 0.70 0.80 0:90 10 


Length-mm— 


Size distribution of the adults and larval stages of Cytheretta tenuipunctata (Bosquet) 


Fic. 19. 
absoluta subsp. nov. 


Cytheretta tenuipunctata lirata subsp. nov. 
(Pl. 14, figs 5, 8-10; Pl. 15, fig. 10; Pl. 16, fig. 4) 
1895 Cytheve juvinei (non. von Munster); Lienenklaus: 8 (pars). 
DERIVATION OF NAME: Latin—lirata, earth or ridge formed by ploughing; refers 


to the ornamentation. 

Dracnosts: A subspecies of C. tenuipunctata in which the full 13 ridges of the 
superspecies C. tenuipunctata are developed; the ornamentation between the ridges 
varies from pitting to reticulation; a weak hinge ear is developed in the left valve. 


HototyPe: Io 3890, a female left valve. 


PARATYPES: Io 3891-95. 
MATERIAL: 37 valves from Auvers-St-George. 


312 MID-TERTIARY CYTHERETTINAE 


TYPE LOCALITY AND HORIZON: Auvers-St-George; Stampian. 
STRATIGRAPHICAL RANGE AND DISTRIBUTION: Stampian of the Paris Basin. 


DESCRIPTION: The shape of the dorsal margin of the left valve is convex with two 
slight concavities to the anterior and posterior of the posterior and anterior hinge 
ears respectively. Otherwise the shape is similar to C. tenuipunctata absoluta. The 
13 ridges are developed, although a few specimens show a smooth area in the antero- 
dorsal region, but this is small. Ornamentation between the ridges shows a large 
amount of variation; pits are usually developed, sometimes in a double row, but 
more often in a single row; in other specimens a fine reticulation is present, and in 
others the longitudinal ridges are very strong with a relatively inconspicuous orna- 
mentation between them. The sub-central plexus is well developed. There is an 
anterior area of reticulation. The inner margin is similar to that of C. tenuipunctata 
absoluta. 


DIMENSIONS: 
Left valve Right valve 
1 H L/H #w ih, H L/H 
Female o0-89+0:03 0:49+0-01 1°82+0-:03 0:29 0:90 0°45 2:00 
Male 0:96 0:49 1-07 0:29 0:98 0:48 2-04 


Discussion: See C. tenuipunctata absoluta subsp. nov. 


Cytheretta tenuistriata (Reuss) 


DracGnosis: A species of the superspecies C. tenuipunctata of large size, with well 
developed sub-central plexus and distinct ornamentation between the ridges. 


Cytheretta tenuistriata tenuistriata (Reuss) 
(Pl. 16, figs 5, 7) 


1853 Cytherella tenuistriata Reuss: 676, pl. 9, fig. ro. 

1905 Cythereis jurvinet (non. von Munster); Lienenklaus: 31 (pars). 
1952 Cythevetta tenuistriata (Reuss); Triebel: 22, pl. 3, fig. 12-15. 
1956 Cytheretta tenuistyviata (Reuss); Oertli: 61, pl. 6, fig. 163-165. 


MATERIAL: Specimens from several localities around Weinheim; Io 3896-7. 
TYPE LOCALITY AND HORIZON: Weinheim, Mainz Basin; Unterer Meeressand. 


STRATIGRAPHICAL RANGE AND DISTRIBUTION: Unterer Meeressand of the Mainz 
Basin, Blaue Ton of Switzerland; Rupelian. 


DIAGNOSIS AND DESCRIPTION: The male has an anterior hinge ear in the left valve 
which, together with the posterior hinge ear, gives the dorsal margin an undulating 
appearance with two concavities. The anterior hinge ear is not present in the 
female, so the dorsal margin of the left valve is regular, and the valve has its greatest 
height close to the anterior end. The ornamentation is not strong; the ridges are 
weakly defined and in between them are double rows of small pits. The anterior 
and posterior areas are smooth. 


OF NORTH-WEST EUROPE 313 


Dimensions (After Triebel): 


L Female I-08-1:'I13mm 
Male I:22-1:28mm 


Discussion: See C. tenuistriata ornata below. 


Cytheretta tenuistriata ornata subsp. nov. 
(Pl. 13, figs 1-12; Text-figs 17, 20) 


1852 Cythere jurinei var. tenuipunctata Bosquet: 56 (pars). 
1895 Cytherve jurinei (non. von Munster); Lienenklaus: 8 (pars). 


DERIVATION OF NAME: Latin—-orno, ornamented; refers to the strong ornamenta- 
tion. 


Draenosis: A subspecies of C. tenwistriata with strong ornamentation. 

Ho otyPeE: Io 3898, a female left valve. 

PARATYPES: Io 4020-7. 

MATERIAL: 32 valves from Auvers-St-George, 3 valves from Morigny; Io 3899. 
TYPE LOCALITY AND HORIZON: Auvers-St.-George ; Stampian. 


STRATIGRAPHICAL RANGE AND DISTRIBUTION: Stampian of Auvers-St.-George, 
Jeurre, and Morigny in the Paris Basin. 


DeEscRIPTION: The dorsal margin of the left valve of both the male and the female 
is almost straight with two slight concavities, one to the anterior of the posterior 
hinge ear and the other to the posterior of the weakly developed anterior hinge ear. 
The anterior margin is evenly rounded; the ventral margin is concave; and the 
posterior margin is obliquely rounded. In the right valve two concavities are present, 
one at the postero-dorsal angle and the other at the antero-dorsal angle. 

The ridges are well developed and broad; there is a well marked anterior zone of 
reticulation. The ornamentation between the ridges consists of puncta arranged 
in three rows, or two rows between the ventral ridges. The sub-central plexus is 
large and prominent. 

The inner margin has three broad indentations; the posterior segment has a greater 
slope than the median segment. 

Three larval stages have been recognized, no. 6, 7, and 8. Ridges are weakly 
developed, being stronger in the right valve than in the left. In no. 8 all the ridges 
are present with a similar arrangement to those of the adult; there is a fine punctation 
between them. In no. 7 only the more ventral ridges are seen (ridges 4-13), and in 
no. 6 a few very faint lines can be seen in the postero-ventral region, where there is a 
slight swelling. 


DIMENSIONS: 

Length of combined left and right valves: 
Female I-05 + 0-01 
Male I'I5 + 0:03 


314 MID-TERTIARY CYTHERETTINAE 


Left valve Right valve 
L H L/H 4W iL, H L/H 
Female 1:03 0:58 1-78 0:31 I-02 0-51 2°00 
Male I'I5 0:58 1-98 0:31 I-14 0:56 2°04 


Mean length of larval stages: 
No. 8, 0:88; no. 7, 0°74; no. 6, 0-61. 
Discussion: This differs from C. tenwistriata tenuistriata (Reuss) in the stronger 
ornamentation. The ridges are much more pronounced, there are no smooth area 


in the anterior and posterior regions, and the pitting between the ridges is finer than 
in C. tenuistriata tenuistriata. See also C. tenuipunctata and C. minipunctata sp. nov. 


Fic. 20. Cytheretta tenuistriata (Reuss) ovnata subsp. nov.; female right valve; x75. 


Cytheretta minipunctata sp. nov. 
(Pl. 16, figs 1-3) 


DERIVATION OF NAME: Latin—minus, small; punctata, small pits; refers to the 
ornamentation. 


Dracnosis: A species of the superspecies C. tenwipunctata with six faint ridges and 
a finely punctate ornamentation. 


HototyPe: Io 4028, a female left valve. 
PARATYPE: Io 4029. 
MATERIAL: 9 valves and carapaces from Cormeilles. 


TYPE LOCALITY AND HORIZON: Cormeilles-en-Parisis; Bed no. 44 of Albissin, 
Couches de Sannois superieur. 


STRATIGRAPHICAL RANGE AND DISTRIBUTION: Lower marine Sannoisian of the 
Paris Basin. 


DEscRIPTION: The dorsal and ventral margins of the left valve are sub-parallel 
and almost straight; a posterior hinge ear is developed; the anterior margin is 
obliquely rounded towards ventral; the posterior margin is slightly pointed. In the 


OF NORTH-WEST EUROPE 315 


right valve, the dorsal margin is convex and the ventral margin concave. In both 
valves there is an elongate dimple in the postero-ventral region. 

Ornamentation consists of some 6 faint ridges which are developed in the ventral 
half of the valve, particularly in the median portion. In between the ridges are 2 or 
3 rows of puncta; these also cover a large part of the dorsal area of the valve, where 
ridges are not developed. 

Details of the interior are not clearly seen. 


DIMENSIONS: 
ie H L/H Ww 
(Average) 
Carapaces—Female 0:94-1:00 0-54-0'58 I-74 0-48 
Male I-IO-I°15 0:58 1:93 0°50 


Discussion: This shows resemblances to C. tenuistriata tenuistriata in size and 
shape, but the ornamentation is completely different. The ornamentation is 
similar to that of C. buttensis buttensis subsp. nov, but has fewer ridges and is a 
different shape. 


Cytheretta buttensis sp. nov. 


DERIVATION OF NAME: French—butte, a hill; refers to the Butte de Cormeille and 
other buttes of the Paris region where the Sannoisian is found. 


Dracnosis: A species of the superspecies C. tenuipunctata showing great variation 
in the development of ridges and ornamentation. There are usually rows of small 
puncta between weak ridges; sometimes reticulate. 


DEscripTION: The left valve has a posterior hinge ear, almost straight dorsal 
margin, evenly rounded anterior margin, straight ventral margin, and tapered 
posterior. The dorsal margin of the right valve is strongly convex, with its greatest 
height in about the centre. There is a dimple in the postero-ventral region of both 
valves. Ovate in dorsal view. 

The inner margin (Text-fig. 21) is fairly regular; the posterior and anterior indenta- 
tions are large, the anterior segment is flat, and the joint median and posterior 
segments have a gentle slope. 

The larval stages are very triangular in shape with a pointed posterior end. The 
ornamentation is similar to that of the adults. 

Three morphotypes have been recognized, which constitute two subspecies (Text- 
fig. 22). 


Morphotype A: 


This is characterized by the development of longitudinal ridges, usually stronger 
in the right valve. These follow the basic pattern of the superspecies; no. 7, with a 
sinuous course, joins no. 9 just before the anterior area of the reticulation; no. 8 joins 
no. 7 as a faint ridge. Between the ridges are parallel rows of small puncta; there 
are three rows between the ridges in the median and dorsal part of the valve and two 
in the ventral part. The sub-central plexus is only weakly developed. 


316 MID-TERTIARY CYTHERETTINAE 


Morphotype B: 


Similar to Morphotype A except for the development of faint cross ridges between 
the longitudinal ones. The surface between the ridges is punctate, as in Morpho- 


type A. 


Morphotype C: 


Strong cross ridges are developed between the longitudinal ones, which gives the 
valve a reticulate appearance. The surface between the ridges is smooth. The 
sub-central plexus 1s very weak. An additional ridge 1s present between no. 2 and 3. 


Cytheretta buttensis buttensis subsp. nov. 
(Pl. 15, fig. 10) 
1960 Cytheretta tenuistviata Mehrotra (non Reuss) p. 80, pl. 1, figs 11-12. 


DIAGNOSIS AND DESCRIPTION: This consists entirely of Morphotype A. 

Ho.ortyPe: Io 4030. 

PARATYPE: Io 4031. 

MATERIAL: See fig. 22. 

TYPE LOCALITY AND HORIZON: Cormeilles-en-Parisis; Bed no. 46 of Mlle. Albissin, 
Couches de Sannois Supérieur. 

STRATIGRAPHICAL RANGE AND DISTRIBUTION: Couches de Sannois supérieur. 


DIMENSIONS (Carapace) 
H L/H Ww 


Female 0-92 +0:04 o51 +002 1:80+0-04 0-48 
Male I'02 +0:04 0°52 +002 1:95 + 0:03 0°45 


Cytheretta buttensis reticulata subsp. nov. 
(Pl. 15, figs 1-8; Text-fig. 21) 
DERIVATION OF NAME: Latin—reticulatus, net-like; refers to the ornamentation. 


DIAGNOSIS and DESCRIPTION: Consists predominantly of Morphotype C together 
with Morphotypes A and B. 


Ho.ortyPe: Io 4032. 

PARATYPES: Io 4033-8. 

MATERIAL: See Fig. 22. 

TYPE LOCALITY AND HORIZON: Cormeilles-en-Parisis; Bed no. 47 of Mlle. Albissin, 
Couches de Sannois supérieur. 

STRATIGRAPHICAL RANGE AND DISTRIBUTION: Couches de Sannois supérieur- 
Marnes a Huitres infeérieurs. 


OF NORTH-WEST EUROPE 317 


DIMENSIONS: (Carapace) ; 
iD H L/H WwW 
Female 0-85 + 0:025 0-48 +001 1:79 40:03 0:42 
Male 0:97 + 0°02 0O50+00I 1:94 +0:03 0°43 


Fic. 21. Cythevetta buttensis reticulata sp. subsp. nov.; female left valve; x75. 


Discussion: Morphotype A resembles C. bernesis Oertli from the Rupelian of 
Switzerland; they differ in dorsal outline, as C. bernesis is tapered towards the 
anterior. The longitudinal ridges are also unequally developed in the latter; ridges 
no. 3 is strong, while nos. 4, 5 and 6 are weak, and they also form a slightly different 
pattern. C.vamosa sublaevis Triebel from the Chattian Cyrenenmergel of the Mainz 
Basin is similar, but the longitudinal ridges are very weak and can hardly be seen in 
the right valve; the surface of the valve is also more uneven, with marked longi- 
tudinal swellings in the position of ridges nos. 4 and 9; these swellings are much more 
apparent in C. ramosa ramosa (Lienenklaus). 


MORPHOTYPE ‘°/o Subspecies 


SAMPLE 


23 (79) 33 19 48 
reticulata 
24 (72) 23 7 70 


Fic. 22. Distribution of morphotypes of Cytheretta buttensis sp. nov. from Cormeilles. 
Note that the stratigraphical sequence has youngest at the bottom. 


COUCHES 
DE SANNOIS 


MARNES 
A HUITRES 


318 MID-TERTIARY CYTHERETTINAE 


DISCUSSION OF THE SUPERSPECIES ¢C. LPENUIPUNCTATLA 


The stratigraphically arranged series of specimens from the Paris Basin shows 
certain trends. The earliest species, C. minipunctata sp. nov. and C. buttensis sp. 
nov. buttensis subsp. nov., have very weakly developed ridges with several rows of 
puncta between them. In the later species the ridges become stronger and the 
puncta in between them become larger with fewer rows, as in C. tenuipunctata 
absoluta and C. tenuipunctata livata. In the latter the ridges are very strong and the 
pitting is reduced to a single row of large pits. 

It is considered that the relationships suggested in Fig. 23 represent a possible 
phylogeny. 

The barrier may be ecological rather than geographical sensu stricto. C. mintpunc- 
tata, or something like it, is a possible ancestor of C. tenuistriata with its two recorded 
geographical sub-species. 

It is interesting to note that in Switzerland the finely punctate species with weak 
ridges, C. variabilis and C. bernesis, occur at a stratigraphically lower horizon than 
C. tenuistriata tenuistriata, as in the Paris Basin. In the Mainz Basin these postu- 
lated early forms are not present, possibly because the Sannoisian is poorly exposed, 
but more likely because they were not present in the area; they have not been found 
in samples collected nor recorded in the works of Triebel, Stchepinsky and Gramann. 
In the Chattian of the Mainz Basin there are, however, two finely punctate forms, 
C. ramosa ramosa (Lienenklaus) and C. vamosa sublaevis (Triebel). The valve of the 
former has an uneven surface, similar to C. variabilis, and both of these are only 
tentatively included in the superspecies. C.vamosa sublaevis has a much smoother 
valve with fine punctae between weak ridges. 

C. stigmosa Triebel has a similar ridge pattern, but varies in shape and has much 
larger pitting. The two must be closely related, however. 

The L/H ratio of all the female left valves from the Paris Basin were averaged, and 
gave an answer of I-79 + 0-04. 


FALUN 
C.tenuipunctata lirata DE 
D JEURRE 
¢, tenuipunctatastenuipunctatal| 5 9) Pa 9) pe 0 
(BELGIUM) 2 C. tenuipunctata absoluta MARNES 
s A 
ic 
< HUITRES 
£ pas. SS 
5 C. buttensis reticulata 
Hypothetical form Ee COUCHES 
o 
oO DE 
C. buttensis buttensis SANNOIS 


Fic. 23. Suggested relationship between Cytheretta buttensis sp. nov. and Cythevetta 
tenuipunctata (Bosquet). 


OF NORTH-WEST EUROPE 319 


This standard deviation compares favourably with that of individual species, so 
it is concluded that this is a further character to be considered in diagnosing the 
superspecies. 

C. minor (Lienenklaus), C. stigmosa Triebel and C. regularis sp. nov. show similari- 
ties to the superspecies C. tenutpunctata (Bosquet) in ornamentation, but differ in 
shape. C. posticalis Triebel has a similar shape to C. tenuipunctata but has almost no 
ornamentation. 


Cytheretta minor (Lienenklaus) 
(Pl. 16, fig. 6) 


1905 Cythereis jurinei (von Munster) var. minor Lienenklaus, p. 32. 
1952 Cythevetta minor (Lienenklaus) Triebel, p. 24, pl. 4, figs. 22-3. 


Diaenosis: A small species of the genus Cytheretta with smooth dorsal and antero- 
dorsal areas and double rows of puncta between weak ridges. 


MATERIAL: 25 valves and carapaces from Weinheim (Trift). Io 3704. 
TYPE LOCALITY AND HORIZON: Weinheim; Unterer Meeressand. 


STRATIGRAPHICAL RANGE AND DISTRIBUTION: Mainz Basin, Unterer Meeressand; 
Paris Basin, Couches de Sannois supérieur. Falun de Morigny. 


DescripTION: In the left valve there is a posterior hinge ear; the dorsal margin is 
very slightly convex and the greatest height is about one quarter of the way from the 
anterior. The anterior margin is obliquely rounded; the ventral margin is almost 
straight and the posterior margin is slightly tapered. In the right valve the dorsal 
margin is slightly convex and the ventral margin is concave. A few denticles are 
present along the anterior margin of the right valve. Ovate in dorsal view. 

The dorsal and antero-dorsal regions are smooth, so that ridges no. 1 and 2 are 
absent. To the anterior of the sub-central plexus ridges b and c are prominent, but 
where ridge a would be is a diffuse area of puncta. There is a double row of 
puncta between the ridges. In most specimens the ridges are merely areas without 
puncta, but this gap between the double rows of pits is greater than that between the 
contained single rows. In a few specimens, however, actual ridges are present. 


DIMENSIONS: (Carapaces). 


iG H L/H Ww 
Female 0-88 0°53 1:66 0°45 
Male 0°85 0:50 1-70 0°43 


Discussion: This could be included in the superspecies due to the similarity of the 
ridge pattern, even though ridge no. a is absent. The size seems to vary; the 
dimensions given by Triebel are less than those of the material examined from 
Weinheim, where it is the commonest Cytheretta species; those from the Paris Basin 
are in better agreement with Triebel. It shows a great resemblance to C. tenwistriata 
tenuistriata (Reuss), with which it is associated in the Mainz Basin. It is much 
smaller, however, and there are no specimens of intermediate size; it has a slightly 
different shape, and lacks ridge a. 


320 MID-TERTIARY CYTHERETTINAE 


Cytheretta posticalis Triebel 


Diacnosis: A large species of Cytheretta with an elongate shape, sub-parallel 
dorsal and ventral margins, and prominent posterior hinge ear. It is almost smooth, 
with a faint ornamentation of ridges and puncta in the posterior and ventral parts of 
the valve. 


Cytheretta posticalis posticalis Triebel 


1905 Cytherers juvinu Lienenklaus (non von Miinster), p. 31. 
1952 Cytheretta posticalis Triebel, p. 23, pl. 3, figs 18-21. 
1956 Cytheretta posticalis Triebel, Oertli, p. 59, pl. 6, figs 160-162. 


TYPE LOCALITY AND HORIZON: Welschberg (Mainz Basin), Unterer Meeressand. 


STRATIGRAPHICAL RANGE AND HORIZON: Mainz Basin: Unterer Meeressand, 
Schleichsand, Cyrenenmergel ; Switzerland: Meeressand, Blaue Tone (both Rupelian). 


Cytheretta posticalis parisiensis subsp. nov. 
(Pl. 18, figs 1-4, 6) 
DERIVATION OF NAME: Named after Paris. 


Diacnosis: A subspecies of C. posticalis showing a large amount of variation in 
areas of ornamentation. 


HototyPeE: Io 4039. 
PARATYPES: Io 4040-42. 
MATERIAL: 22 valves from Auvers-St.-George; 5 from Morigny. 


TYPE LOCALITY AND HORIZON: Auvers-St.-George, Stampian. 


STRATIGRAPHICAL RANGE AND DISTRIBUTION: Auvers-St.-George, Morigny; 
Stampian of the Paris Basin. 


DESCRIPTION: Sexual dimorphism is pronounced, the males being more elongate. 
The left valve has a strong posterior hinge ear and a weak anterior one; this causes the 
dorsal margin to have an undulating appearance. This is particularly true of the 
male. The anterior margin is evenly rounded; the ventral margin, almost parallel to 
the dorsal, is slightly concave in the male and convex in the female. The posterior 
margin is tapered. In the right valve the dorsal margin is almost straight and the 
ventralis concave. It is ovate in dorsal view. 

The ornamentation varies. Some specimens are completely smooth; some have 
a few faint double rows of puncta in the ventral portion of the postero-median 
region; others have a few faint ridges with puncta between in the postero-ventral 
angle. 

The internal features are as for the superspecies C. tenuipunctata with inner margin 
similar to C. tenuistriata ornata. 


Discussion: C. posticalis posticalis differs only in the ornamentation, which is 
restricted to a few ridges in the postero-ventral angle. Some specimens of 


OF NORTH-WEST EUROPE 321 


C. posticalis parisiensis are exactly the same, but the great variation within the 
sample is taken to indicate subspecific differentiation. 

C. klahni Stchepinsky from the Stampian Marnes a Cyrénes of Alsace has orna- 
mentation confined to the median and posterior parts of the valve and consists of 
double rows of small puncta. In this respect it is similar to some of the specimens of 
C. posticalis parisiensis. However, the lateral outline has a rhomboidal appearance 
due to the shape of the posterior margin, which differs from C. posticalis; and in 
dorsal outline it is more tapered. It is much smaller, but is probably a related 


species. 
DIMENSIONS: 
Left valve Right valve 
ie H L/H ie H L/H 
Female 0:95 0°53 1-79 0-91 0°47 1:94 
Male I'05 0°53 1-98 1:03 0-49 2:10 


Cytheretta headonensis Haskins 
(Pl. 18, figs 11-14; Text-fig. 24) 


1857 Cytherideis colwellensis Jones (pars) p. 49, pl. 14, figs 2oa—c. 
1870 Cytheve ? Jones p. 157 and 159. 
1887 Xestolebevis auvantia non Baird, var. Jones and Sherborn, vol. 4, p. 456. 
1889 Cytherideis colwellensis Jones, Jones and Sherborn p. 45. 
1968 Cytheretta vrhenana headonensis, Haskins, p. 167, pl. 3, figs 11-18. 

Diacnosis: An unornamented species of Cytheretta with a strongly obliquely 
rounded anterior margin. 

MATERIAL: 3 valves from Headon Hill; 16 from Colwell Bay; 17 from Milford; 
7 from Whitecliff Bay. Io 4043-7. 

TYPE LOCALITY AND HoRIzON: Although there are grounds for believing that 
Headon Hill is the type locality due to etymology, in the type description Whitecliff 
Bay is quoted; Middle Headon Beds. 


Fic. 24. Cytheretta headonensis Haskins; female right valve; 75 


322 MID-TERTIARY CYTHERETTINAE 


STRATIGRAPHICAL RANGE AND DISTRIBUTION: Middle Headon Beds of Headon Hill, 
Colwell Bay, Whitecliff Bay, and Milford. 


Discussion: This is very similar to C. rhenana Triebel; the left valve of C. headon- 
ensis has a much more obliquely rounded anterior margin, as well as more anterior 
radial pore canals (34 compared with 27). 

Jones figured two different ostracods as his new species Cytheridets colwellensis; all 
of the material is preserved in the British Museum (Nat. Hist.), No. 1 6431 (13). Pl. 4, 
fig. 13 of Jones is a species of Neocyprideis, which has now been selected as the lecto- 
type to avoid taxonomic complications, even though the type is a moult stage and 
thus not very satisfactory; fortunately it is a very common species so that its diag- 
nosis is possible with topotype material of the adult. 


Cytheretta vesca sp. nov. 
(PL 27; figs:S) Oyar2) 


DERIVATION OF NAME: Latin—vescus, weak, little; refers to the fragile appearance 
of the carapace. 


DiaGnosis: A species of Cytheretta with a thin shell and a weak ornamentation 
consisting of rows of small puncta in the posterior and latero-ventral areas of the 
carapace. 


HoLotyPeE: Io 4048, a female left valve. 

PARATYPES: Io 4049-51. 

MATERIAL: 9g valves. 

TYPE LOCALITY AND HORIZON: Auvers-St.-George; Stampian. 


STRATIGRAPHICAL RANGE AND DISTRIBUTION: So far known only from the type 
locality. 


DESCRIPTION: Sexual dimorphism is distinct, the males being more elongate; sex 
ratio 1:1. The left valve has a weak posterior hinge-ear and a convex dorsal 
margin; the anterior margin is obliquely rounded; the ventral margin is straight; 
the posterior margin is obliquely rounded, particularly in the female. The ventral 
margin of the right valve is concave. The carapace is ovate in dorsal view. 

The ornamentation consists of a few indistinct rows of very small puncta in the 
posterior and latero-ventral areas of the carapace. 

The hinge of the left valve has a small antero-dorsal lobe, although the corres- 
ponding antero-dorsal platform of the right valve is very prominent. The antero- 
ventral lobe is weak; the antero-median tooth is small. The postero-median swelling 
is prominent in lateral view, but cannot be seen in dorsal view. The anterior tooth 
of the right valve is large, projecting beyond the dorsal margin; the posterior tooth is 
equally prominent in dorsal view, but smaller in lateral view. 

The selvage forms the anterior margin; along the ventral margin there is a promin- 
ent flange and a wide flange groove; there is a narrow flange groove along the pos- 
terior. A list is present. There are some 45 normal pore canals, but the number of 
radial pore canals could not be determined, nor could the shape of the inner margin. 


OF NORTH-WEST EUROPE 323 


DIMENSIONS: 
Left valve Right valve 
ib H L/H 6, H L/H 
Female 0°73 0°42 1°74 0-72 0°37 1°95 
Male 0-70 0:38 1-84 0°70 0°33 212 


Discussion: This differs from C. rhenana in having a weak ornamentation. The 
ornamentation is much weaker than that of C. stigmosa. It differs from both of 
these in shape; the dorsal margin of the left valve is more convex and the posterior 
margin is more obliquely rounded. The carapace ot C. vesca is much less massive 
than these. 


Cytheretta stigmosa Triebel 


Diacnosis: A species of the genus Cytheretta with an obliquely rounded anterior 
margin. The ornamentation consists of longitudinal rows of large pits with ridges 
in between which become stronger ventrally. 


Cytheretta stigmosa stigmosa Triebel 
1952 Cytheretta rhenana stigmosa Triebel, p. 26, pl. 5, figs 28, 29. 


TYPE LOCALITY AND HORIZON: Welschberg; Unterer Meeressand. 


STRATIGRAPHICAL RANGE AND DISTRIBUTION: Rupelian Meeressand and Schleich- 
sand of the Mainz Basin. Cavelier (1965, determinations by Apostolescu) records it 
from the Sannoisian of Sannois in the Paris Basin. 


Discussion: See C. stigmosa gallica sub sp. nov. 


Cytheretta aff. stigmosa stigmosa 
(Pl. 16, fig. 8) 


LOCALITY AND STRATIGRAPHICAL POSITION: Whitecliff Bay, Isle of Wight; Middle 
Headon, Beds (WB18). Io 4052. 

Discussion: Six poorly preserved specimens, together with one well preserved one, 
were available for study. No internal characters could be seen. The shape is 
similar to C. stigmosa. The ornamentation is very similar except that the pits are 
rather smaller and there are more of them per row than in C. stigmosa stigmosa. The 
dorsal and antero-dorsal regions are smooth. It is unknown whether this is a 
distinct subspecies or the same as that from the Rhine Valley. 


Cytheretta stigmosa gallica subsp. nov. 
(Pl. 17, Figs 1, 2, 5, 10; Text-fig. 25) 
DERIVATION OF NAME: Latin—Gallica, country of the Gauls. 


Diacnosis: A subspecies of C. stigmosa in which the ornamentation covers the 
whole valve and the longitudinal ridges are very narrow. 


324 MID-TERTIARY CYTHERETTINAE 


HototyPeE: Io 4053, a female left valve. 

PARATYPES: Io 4054-56. 

MATERIAL: 44 valves, 4 carapaces. 

TYPE LOCALITY AND HORIZON: Auvers-St-George ; Stampian. 


STRATIGRAPHICAL RANGE AND DISTRIBUTION: So far only known from the type 
locality. 


DESCRIPTION : Sexual dimorphism can be observed, the males being more elongate; 
sex ratio, 1: 1°5. The left valve has a posterior hinge ear; the dorsal margin is 
convex with the greatest height of the valve in line with the sub-central plexus. The 
anterior margin is obliquely rounded; the ventral margin is almost straight; the 
posterior margin is obliquely rounded, but only slightly so. In the right valve the 
ventral margin is concave. 

Ridges with pitting between them are present in the ventral part of the valve and 
would correspond to ridges nos. 7-13 in the terminology adopted for C. tenuipunctata; 
ridges b and c can also be seen. In the median and dorsal areas are some seven 
longitudinal rows of large pits with weak and irregular ridges between them. There 
is an area of small pits, not arranged in rows, in the antero-dorsal region; to the an- 
terior of the poorly defined sub-central plexus is an area of larger pits, while along 
the anterior margin there is reticulation. 

In the hinge of the left valve the antero-dorsal lobe is slightly swollen; the antero- 
ventral lobe is small; the antero-median tooth is small but prominent; and the 
postero-median swelling is of equal size and prominence as the antero-median tooth. 

The selvage runs close to the anterior and posterior margins so that there is only a 
very small flange groove present in these regions which is better seen in the right 
valve. Along the ventral margin of the right valve there is a wide flange groove. 

The inner margin has a beak-shaped anterior indentation, prominent ventral, and 
a high and fairly narrow posterior indentation. The anterior segment is gently 
rounded, the median is short and curves into the steep posterior indentation. The 
distribution of pore canals could not be seen. 


Fic. 25. Cytheretta stigmosa Triebel gallica subsp. nov.; male left valve; x75. 


OF NORTH-WEST EUROPE 325 


DIMENSIONS: 
L H L/H Ww 
Female 0-75 0°47 I-57 0:38 
Male 0-74 0°42 I-76 0:36 


Discussion: C. stigmosa stigmosa has unornamented dorsal and antero-dorsal 
areas and smaller pits with wider areas between the rows. Thus it differs from the 
almost reticulate appearance of C. stigmosa gallica. C. minor is rather similar but has 
double rows of puncta instead of single rows of large pits and unornamented areas as 
in C. stigmosa stigmosa; its lateral outline is also different. See also C. regularis sp. 
nov. and C. bullans sp. nov. 

C. stigmosa is here regarded as a separate species rather than a subspecies of 
C. rhenana because the two are found together and should therefore be regarded as 
distinct species or as varieties or morphotypes of a single species. There is also a 
lack of intermediaries and the difference cannot be sexual because sexual dimor- 
phism can be recognized with each group. It should be pointed out, however, that 
small unornamented forms and pitted forms similar to C. rhenana and C. stigmosa are 
found together not only in the Rhine Valley, but in the Paris Basin, Aquitaine Basin 
and the Hampshire Basin. They do not always occur in the same sample, but do 
occur at the same locality and in adjacent horizons. They perhaps inhabited differ- 
ent ecological zones and could represent ecologically separated subspecies. As this 
is not proven, the evidence still favours them as distinct species. 


Cytheretta regularis sp. nov. 
(Pl. 17, figs 3, 4, 6, 7; Text-fig. 26) 

DERIVATION OF NAME: Latin—regularis, regular; refers to the smooth and regular 
lateral outline of the left valve. 

Diaenosis: A species of Cytheretta with a straight dorsal margin in the left valve, 
sub-parallel dorsal and ventral margins, and an evenly rounded posterior margin. 
Ornamentation consists of longitudinal rows of pits with a smooth antero-dorsal 
region. Sexual dimorphism is not pronounced. 

HototyPe: Io 4057. 

PARATYPES: Io 4058-60. 

MATERIAL: 12 valves and carapaces from Espibos, 6 from Lesbarritz. 

TYPE LOCALITY AND HORIZON: Lesbarritz, Gaas (AGLI); Stampian. 

STRATIGRAPHICAL RANGE AND DISTRIBUTION: Lesbarritz and Espibos, Gaas; 
Stampian. 

DESCRIPTION: Sexual dimorphism is not very pronounced, the males being slightly 
more elongate; sex ratio 1:2. The dorsal margin of the left valve is straight with 
no posterior hinge ear; the anterior margin is slightly obliquely rounded; the ventral 
margin is almost straight ; and the posterior margin is evenly rounded. In the right 
valve the dorsal margin is convex and the ventral is concave. The dorsal and 
ventral margins are almost parallel. In dorsal view the carapace is ovate. 


326 MID-TERTIARY CYTHERETTINAE 


The ornamentation consists of 13 longitudinal rows of pits between narrow 
ridges. The sub-central plexus is fairly prominent although not appearing so in the 
electron scanning photographs, and to its anterior are two prominent ridges which 
slope towards the antero-ventral angle. The anterior and posterior regions are 
covered by numerous small pits. The extreme antero-dorsal area is smooth. 

In the hinge of the left valve the antero-dorsal lobe is small and slightly swollen; 
the antero-ventral lobe is poorly developed; the antero-median tooth is small and 
the postero-median swelling is hardly noticeable. In the right valve the anterior 
tooth is much smaller and globose in shape. 

The selvage is very close to the margins of the valve with a flange groove developed 
along the ventral margin and a small one along the posterior margin. The inner 
margin has three prominent indentations; the anterior one is rather ill defined 
in the specimens available, but is narrow; the ventral one is very long and narrow; 
the posterior one is small. The anterior segment is unevenly rounded; the median 
segment is short with a gentle curve; the posterior segment is long with a fairly steep 
slope. There are some 27 anterior radial pore canals, tending to be grouped into 
five sets; 35 closely spaced posterior radial pore canals; 10 ventral radial pore canals; 
and some 38 normal pore canals, which are not related to the ornamentation except 
that they mainly open into the pits of the outer surface. 

The central muscle scars are in a slight pit with four equal small and circular 
adductor muscle scars along the posterior edge of the pit and a large frontal muscle 
scar on the anterior edge. The fulcral point is not very prominent. 


DIMENSIONS: 
Left valve Right valve 
L H L/H 8 H L/H 
Female 0-70 0:38 1-84 0:68 0°35 1-94 
Male 0:70 0°37 1°88 0-68 0°33 2:06 


Discussion: This differs from C. stigmosa in shape, particularly of the dorsal 
margin. Theornamentation is very similarto C. stigmosa gallica and also to C. bullans. 
It differs from the latter in the shape of the anterior margin, in size, and in the 
constancy of development of the ornamentation. It differs from C. minor in having 
single rows of large pits instead of double rows of puncta, as well as in shape. 


Fic. 26. Cytheretta vegularis sp. nov.; male right valve; x75. 


OF NORTH-WEST EUROPE 327 


Cytheretta bullans sp. nov. * 
(PION nes 5.77 bl. 22, fg. 1) 


DERIVATION OF NAME: Latin—bulla, bubble; refers to the ornamentation which 
resembles strings of bubbles. 


Dracnosis: A species of the genus Cytheretta with parallel dorsal and ventral 
margins and evenly rounded anterior and posterior margins. Ornamentation 
consists of longitudinal rows of pits often with a large unornamented anterior region. 


HoLotyPeE: Io 4061. 

PARATYPE: lo 4062. 

MATERIAL: 18 carapaces. 

TYPE LOCALITY AND HORIZON: Chateau Romefort, Blaignan; Argile a Algues, 
Sannoisian. 

STRATIGRAPHICAL RANGE AND DISTRIBUTION: Known only from the type locality. 


DESCRIPTION : Sexual dimorphism is distinct, the males being more elongate; sex 
ratio, 1: 2. The dorsal and ventral margins of the left valve are parallel. The 
dorsal margin of the left valve is straight without a posterior hinge ear; the anterior 
margin is evenly rounded; the ventral margin is very slightly concave; the posterior 
margin is evenly rounded. In dorsal view it is ovate with a tapered anterior end. 

The degree of development of the ornamentation varies. There are some thirteen 
rows of pits with ridges between to the posterior of the ill-defined sub-central plexus. 
To the anterior are two prominent ridges which slope towards the antero-ventral 
angle. There is an anterior area of reticulation with small pits in between. The 
antero-dorsal area is smooth. This unornamented anterior area varies in size; in 
some specimens the whole anterior area is smooth and in others the ornamentation is 
restricted to six or seven rows of pits in the postero-median position. It must be 
emphasized that this is not a form of sexual dimorphism, as might be inferred from 
Pi. x8, figs 5, 7. 

Internal characters could not be seen. 


DIMENSIONS: Carapace 


Te H L/H Ww 
Female 0°85 0:48 177 0°43 
Male 0-90 0°45 2:00 0-40 


Discussion: See C. vegularis. It differs from C. stigmosa in lateral shape, and from 
C. minor in having single rows of large pits instead of double rows of puncta, as well 
as in shape. 


Cytheretta sagri Deltel 


Diacnosis: A species of Cytheretta with thirteen longitudinal ridges, often only 
present in the posterior. The inner margin has a characteristic shape with a 
depressed median segment markedly separated from the anterior and posterior 
segments. 


328 MID-TERTIARY CYTHERETTINAE 


DESCRIPTION: Six merphotypes divisible into three subspecies have been recog- 
nized; these are described below. The shape and ornamentation vary to a great 
extent, but the internal structures appear to be constant. Another feature that is 
constant is the five posterior spines. 

The hinge of the left valve has a prominent swollen antero-dorsal lobe; a strong 
antero-ventral lobe; a large antero-median tooth; a very weak postero-median swell- 
ing, and a large posterior socket. In the right valve the anterior tooth is much 
larger than the posterior one. 

The selvage runs very close to the anterior margin; a wide flange groove is present 
along the ventral margin with a narrow one along the posterior. The inner margin 
is very characteristic of the species. The anterior and posterior indentations are 
narrow; the ventral indentation is narrow and ‘V’-shaped. The anterior and 
posterior indentations are semi-circular; the median segment is sharply differentiated 
from these, lying close to the ventral margin and with a postero-ventral indentation. 

There are 25 anterior radial pore canals, 33 posterior, and 14 ventral. The central 
muscle scars are in a pit; the two lowest adductors are almost joined, and the frontal 
is inside the pit. The fulcral point is large and prominent. 


Morphotype A: 


Sexual dimorphism is pronounced, the males being more elongate. The left 
valve has a strong posterior hinge ear and a weak anterior one; the dorsal margin 
between these is symmetrically convex in the female and asymetrically convex in 
the male with the steep slope towards the posterior. The anterior margin is slightly 
obliquely rounded with some nine denticles in the ventral half. The ventral margin 
of the female is straight, while that of the male is concave. The posterior margin is 
evenly rounded. The dorsal margin of the right valve has a marked protuberance 
in the anterior half caused by the high position of the antero-median socket of the 
hinge; the ventral margin is concave. In dorsal view the female is ovate and tapered 
towards the anterior; the male is more bullet-shaped. 

The ornamentation consists of thirteen longitudinal ridges. In the right valve 
ridges nos. 4 and 8 are sometimes very strong with a slight depression developed 
between them. Ridge no. 6 is thin, bifurcating at its anterior end just to the 
posterior of the sub-central plexus, one part joining no. 5 and the other no. 7. This 
ridge is always weak in the right valve, but in some left valves it is strong, stronger 
in fact than no. 7, so that it appears that no. 7 joins it instead of the other way round. 
To the anterior of the weak sub-central plexus are four prominent ridges sloping 
towards the antero-ventral angle. Faint cross-ridges and meandriform punctation 
are developed between the longitudinal ridges (see Pl. 21, fig. 5 for meandriform 
punctation). 


Morphotype B: 


This differs slightly from Morphotype A in shape; it has a more rectangular outline 
due to the evenly rounded anterior margin, and in dorsal view it is ovate, not tapered. 
The whole of the anterior margin is denticulate with some twelve denticles. The 


OF NORTH-WEST EUROPE 329 


ornamentation is similar to that of Morphotype A, except that there is a smooth 
area of varying extent in the antero-dorsal region. The internal details could not 
be seen. 


Morphotype C: 


The female left valve has no anterior hinge ear, so the antero-dorsal angle is a 
smooth curve, unlike Morphotypes A and B. In dorsal view it is ovate. The orna- 
mentation is restricted to the posterior part of the valve where 9-13 ridges can be 
seen. Ridge no. 6 is clearly recognizable and of equal strength to the other ridges. 
No internal details could be seen. 


Morphotype D: 

This is similar in shape to Morphotype C and the ornamentation is also restricted 
to the posterior. It differs in the inequality of the ridges; no. 6 in particular is 
weaker. 


Morphotype E: 


The female left valve has no anterior hinge ear, but the lateral outline of the 
carapace differs from Morphotypes C and D in being almost triangular with a very 
prominent posterior hinge ear. The carapace is unornamented over a large anterior 
and antero-dorsal area; longitudinal ridges are present over the remaining surface 
with a very fine meandriform punctation between them. Ridge no. 6 is very weakly 
developed. This differs from Morphotype B in shape and in having a much weaker 
ornamentation without the cross-ridges present between the longitudinal ridges. 


Morphotype F : 

This is very similar to Morphotype E, except that the ornamentation is restricted 
to the posterior half of the valve. Ridge no. 6 is very faint and thread-like, leaving a 
prominent gap between nos. 5 and 7; in this respect it differs from Morphotype C. 


Cytheretta sagri sagri Deltel 
(Pl. 19, figs. 1-4; text-fig. 28) 
1964 Cytheretta sagvi Deltel, p. 156, pl. 3, figs 56-57. 


DIAGNOSIS AND DESCRIPTION: A subspecies of C. sagvi consisting predominantly of 
Morphotype A with Morphotype D. 

The last two larval stages have been recognized. The ornamentation in no. 8 
consists of two prominent ridges, nos. 4 and 8 of the adult, with the other ridges of 
the adult stage weakly developed. Cross-ridges are sometimes present; puncta are 
present between the ridges. There are four posterior spines and eleven anterior 
denticles, each bearing one of the eleven anterior pore canals. In the seventh larval 
stage the two ridges nos. 4 and 8 are present. There are seven anterior radial pore 
canals and denticles and two posterior spines. 


330 MID-TERTIARY CYTHERETTINAE 


MATERIAL: See fig. 27. Io 4063-6. 
TYPE LOCALITY AND HORIZON: Lesbarritz, Gaas; Stampian. 
STRATIGRAPHICAL RANGE AND DISTRIBUTION: Stampian of Gaas (Lesbarritz 
Espibos) and Bastennes-Gaujacq, Aquitaine Basin. 
DIMENSIONS: 
Morphotype A 
Left valve Right valve 
ik, H L/H 4W 1G H L/H 
Female 084 0:45 1:87 40:22 0:84 0:42 2:00 
Male 0-00" “O47 “"E-9r ~~ 0-247 —'0-g0) Fo-45" 9 2-0G 


Morphotype D (Carapace) : 


Female 0:92 0°53 1-74 0-46 


MORPHOTYPE 
SAMPLE 


RO 270 
RO 271 


Fic. 27. Distribution of Morphotypes of Cytheretta sagvi Deltel. 
Cytheretta sagri inconstans subsp. nov. 


(Pl. 19, figs 5-7, 9) 


DERIVATION OF NAME: Latin—inconstans, the opposite of standing firm, or 
inconstant ; refers to the great variation of shape and ornamentation. 


OF NORTH-WEST EUROPE 331 


DIAGNOSIS AND DESCRIPTION: A subspecies of C. sagri showing variation in shape 
and ornamentation. The latter consists of thirteen longitudinal ridges which in 
some specimens cover the whole valve and in others only the posterior region. It 
consists predominantly of Morphotype C with A and B. 


HototyPe: Io 4067, a female left valve. 

PaRATYPES: Io 4068-70. 

MATERIAL: See fig. 27. 

TYPE LOCALITY AND HORIZON: Chateau Romefort, Blaignan; Argiles a Algues, 
Sannoisian. 

STRATIGRAPHICAL RANGE AND DISTRIBUTION: So far only known from the type 
locality. 


DIMENSIONS: Carapaces 
Morphotype B Morphotype C 
L H L/H Ww L H L/H Ww 


Hemale 078) 0:43. 1:81 0-38 0°92 «0°53 ) 1-74) 0-47 
Male ©788 40°43) “1-93-0309 0-95) 0:47" 2:02" 0742 


Cytheretta sagri martini subsp. nov. 
(Pl. 20, figs 1-4) 


DERIVATION OF NAME: From the Phare St. Martin, Biarritz. 


DIAGNOSIS AND DESCRIPTION: A subspecies of C. sagri of a triangular shape in 
lateral view and with a weak ornamentation. It consists of Morphotypes D, E and 
F, particularly the last two. 


HorotyPe: Io 4071, a female left valve. 
PARATYPES: Io 4072-6. 
MATERIAL: See fig. 27. 


Fic. 28. Cythevetta sagyi Deltel; female left valve. 75 


332 MID-TERTIARY CYTHERETTINAE 


TYPE LOCALITY AND HORIZON: Couches du Phare, Biarritz (RO 270) ; Stampian. 
STRATIGRAPHICAL RANGE AND DISTRIBUTION: So far only known from the type 


locality. 
DIMENSIONS: 
Morphotype E 
Left valve Right valve 
1, H L/H 1G H L/H 
Female 0:83 0°45 1-84 0-81 0-40 2°03 
Male 0-86 0°45 I‘QI 0-90 0°43 2°09 
Morphotype F (Carapace): 
is H L/H w 
Female 0°85 0-47 1-81 0°39 
Male 0-87 0°45 I'93 0:40 


Discussion: C. sagri Deltel may be the form described by Reuss (1869) as Cythera 
multinervis sp. nov. (p. 482, pl. 6, fig. 2). 

The Oligocene of Aquitaine contains a group of closely related species: C. sagrz 
Deltel, C. gibberis sp. nov., C. minipustulosa sp. nov., C. postornata sp. nov., and 
C. samothracia Deltel; C. perita Deltel from the Upper Eocene is perhaps related to 
this group. 

C. sagri (Morphotype A), C. minipustulosa and C. samothracia have an unusual 
meandriform punctation between the longitudinal ridges, but the pattern of the 
ridges differs amongst the three species. C. sagyi (Morphotypes C, D and G), C. 
gibberis, C. perita and C. postornata are similar in that the ornamentation is restricted 
to the posterior. C. gibberis differs in the unusual shape of the right valve with its 
dorsal ““‘hump”’; C. perita differs in shape in having only four posterior spines and in 
the shape of the inner margin; C. postornata also differs in shape and in ornamenta- 
tion, which consists of six sulca, one of which reaches to the centre of the carapace. 

C. tenuipuncta (Bosquet), C. tenuistriata (Reuss) and C. buttensis sp. nov. reticulata 
subsp. nov. are similar to C. sagri (Morphotype A), but have a different ridge pattern 
and lack the characteristic meandriform punctation. C. buttensis reticulata has 
cross-ridges similar to C. sagvi (Morphotypes A and B), but differs by the features 
already mentioned. C. posticalis Triebel has the ornamentation restricted to the 
posterior, but this is much weaker than the omamentation of C. sagvi (Morphotypes 
C, D and G) and is developed in a more ventral position; it also differs in shape. 


Cytheretta samothracia Deltel 
(Pl. 21, figs 5, 6, 8) 
1964 Cytheretta samothvacia Deltel, p. 158, pl. 3, figs 58-60. 


DIAGNOSIS AND DESCRIPTION: Sexual dimorphism is pronounced; the female 
carapace is quadrate in lateral view, the male is rectangular. There are five promi- 
nent posterior spines. Ornamentationconsists ofeleven longitudinal ridges, including 


OF NORTH-WEST EUROPE 333 


two prominent parallel ridges in the median part of the valve and two in the dorsal 
part. Between the ridges is a meandriform punctation and a faint reticulation. 


MATERIAL: 36 valves and carapaces from Biarritz. Io 4077-79. 
TYPE LOCALITY: Bastennes-Gaujacq ; Stampian. 


STRATIGRAPHICAL RANGE AND DISTRIBUTION: Bastennes-Gaujacq, Lourquen; 
Stampian. Couches du Phare, Biarritz; Stampian. 


DIMENSIONS: 
Left valve Right valve 
i H L/H 1 H L/H 
Female 0:95 0:56 1-70 0:95 0°49 I-94 
Male I-04 0°55 1-89 I-00 0°50 2:00 


Discussion: In shape and ornamentation this is easily distinguished from other 
species of Cytheretta. See also C. sagri and C. minipustulosa. 


Cytheretta minipustulosa sp. nov. 
(Pl. 21, figs 1-4; Text-fig. 29) 
DERIVATION OF NAME: Latin—mini, small; pustulosa, full of pimples; refers to 
the ornamentation between the longitudinal ridges. 


Draenosis: A species of Cytheretta with eleven longitudinal ridges, four of which 
join in the anterior to form two concentric ovals open towards the posterior. Between 
the ridges are faint cross-ridges and a meandriform punctation. 


Ho.otyPe: Io 4080, a male right valve. 

PARATYPES: Io 4081-83. 

MATERIAL: I5 valves and carapaces from Biarritz; 1 valve from Gaas. 

TYPE LOCALITY AND HORIZON: Biarritz; Couches du Phare superieur. 

STRATIGRAPHICAL RANGE AND DISTRIBUTION: Couches du Phare, Biarritz 
(Stampian); Espibos (Gaas), Stampian. 

Description: In lateral view the carapace is rectangular. Sexual dimorphism is 
not very pronounced, the males being more elongate. The left valve has a posterior 


Fic. 29. Cytheretta minipustulosa; male right valve; x75. 


334 MID-TERTIARY CYTHERETTINAE 


hinge ear and a weak anterior one; the dorsal margin between is slightly convex. 
The anterior margin is almost evenly rounded. The ventral margin is slightly con- 
cave, particularly in the male. The posterior margin is evenly rounded with five 
spines. In the right valve the dorsal margin has a protuberance due to the high 
position of the antero-median socket. The ventral margin is concave; the posterior 
has five spines, and there is a marked concavity in the postero-dorsal angle. In 
dorsal view the female is tapered, while the male has more or less parallel sides. 

Ornamentation consists of eleven longitudinal ridges. Ridges nos. 2 and 6, and 
nos. 3 and 5 join in the anterior and form two concentric ovals, open towards the 
posterior. Ridge no. 4, which is weak, runs down the centre. Nos. 5 and 6 join 
towards the posterior. Between the longitudinal ridges are faint cross-ridges and a 
meandriform punctation. There is no sub-central plexus. 

The hinge of the left valve has a swollen antero-dorsal lobe; a strong antero-ventral 
lobe ; a deep anterior socket ; a small antero-median tooth; and a weak postero-median 
swelling. In the right valve the anterior tooth is large and pointed; the posterior 
tooth is small. 

The selvage is strong. It runs close to the anterior margin but a small flange 
groove is present; the flange groove along the ventral margin is not large. The 
selvage is very strong in the posterior forming a projecting ridge, to the posterior of 
which is the flange groove. The latter has more the appearance of a platform; the 
flange is weak. 

The inner margin has a characteristic shape. The anterior and posterior segments 
are narrow and deep; the ventral indentation is small, but because of the shape of the 
posterior segment it 1s very prominent. The anterior segment is semi-circular; the 
median segment is small and overshadowed by the steeply curved posterior segment, 
which sweeps up close to the dorsal margin. 

The two lower adductor muscle scars touch; the third is elongate; the topmost one 
is triangular. The fulcrum is not very prominent. No pore canals could be seen. 


DIMENSIONS: 
Left valve Right valve 
L H L/H Ww 1g H Ue 
Female 0:88 0-48 1°83 — 0-98 0-48 2:04 
Male I-00 0-48 2:08 0:40 I-09 0-50 2-18 


Discussion: This differs from C. sagvi Deltel by the ridges which form two con- 
centric ovals open towards the posterior, in its elongate shape, and in the shape of the 
inner margin. It differs from C. samothracia Deltel in lacking the two sets of paired 
ridges, as well as in its more elongate shape. 


Cytheretta gibberis sp. nov. 
(Pl. 16, figs 9, 10; Pl. 19, figs 10) 


DERIVATION OF NAME: Latin—gibberis, hump on the back; refers to the shape of 
the female right valve. 


OF NORTH-WEST EUROPE 335 


DiaGnosis: A species of Cytheretta in which the right valve of the female is very 
high in the posterior. Ornamentation is restricted to the posterior and consists of 
twelve radial sulca, the central one being longer than the others. 


HorotyPe: Io 4084, a female right valve. 

PARATYPES: lo 4085-86. 

MATERIAL: g valves and carapaces. 

TYPE LOCALITY AND HORIZON: Couches du Phare superieur (RO 271), Biarritz. 


STRATIGRAPHICAL RANGE AND DISTRIBUTION: So far only known from the type 
locality. 


DESCRIPTION: Sexual dimorphism is distinct, particularly in the right valve. The 
left valve has a weak posterior hinge ear, in front of which is a slight concavity; the 
remainder of the dorsal margin is convex. The anterior margin is obliquely rounded ; 
the ventral margin is straight; the posterior margin is evenly rounded with a few 
small spines. The right valve of the temale has a very high posterior dorsal margin, 
which over-reaches the left valve in the position of the concavity adjacent to the 
hinge ear. The dorsal margin slopes steeply to the position of the anterior tooth, in 
front of which is a concavity with the antero-dorsal platform of the hinge. The 
anterior margin is evenly rounded; the ventral margin is straight. The ventral part 
of the posterior margin bears some four spines, although the exact number could not 
be determined; in the dorsal part there is a large concavity. The right valve of the 
male is not so high posteriorly and has a concave ventral margin. In dorsal view the 
carapace is ovate. 

The ornamentation is restricted to the posterior and consists of some eleven short, 
radiating sulca with a long central one which reaches to the central region of the 
carapace. There is a slight postero-ventral depression in the right valve. 

Owing to the poor preservation of the material, the internal features could not be 
completely observed. The hinge of the left valve has a strong antero-dorsal lobe and 
a prominent antero-median tooth. The right valve has a large antero-dorsal plat- 
form and a large anterior tooth; the posterior tooth is fairly small and lies along the 
postero-dorsal concavity, almost at right angles to the dorsal margin. 

The selvage is prominent with a wide flange groove along the anterior, ventral and 
posterior of the right valve. A weak list is present in the anterior and postero-ventral 
regions. The inner margin could not be clearly seen; the anterior and posterior 
indentations are deep and narrow; and the anterior segment is short and semi- 
circular. 


DIMENSIONS: 
Carapace Right valve 
L H L/H W IE, H L/H 
Female 0:86 0°52 1-65 0°43 0:88 0:48 1°83 
Male a — — ~ 0:92 0°47 I-96 


Discussion: The shape of the female right valve distinguishes this form from all 
other Cytheretta spp. in which the ornamentation is restricted to the posterior. 


336 MID-TERTIARY CYTHERETTINAE 


Cytheretta postornata sp. nov. 
(Pl. 20, figs 5-8; Pl. 22, fig. 12) 


DERIVATION OF NAME: Latin—post, posterior; ornata, ornament; refers to the 
ornamentation which is restricted to the posterior. 


Diacnosis: A species of Cytheretta in which the ornamentation is restricted to the 
posterior. This consists of 6-8 prominent sulca, one of which reaches to the centre 
of the carapace. 


HototyPe: Io 4087, a female left valve. 

PARATYPE Io 4088. 

MATERIAL: IO carapaces. 

TYPE LOCALITY AND HORIZON: Biarritz; Couches de l’Atalaye (RO 264). 

STRATIGRAPHICAL RANGE AND DISTRIBUTION: So far only known from the type 
locality. 

DESCRIPTION: Sexual dimorphism is not very strong. The dorsal margin of the 
left valve is strongly convex, less soin the right valve. The anterior margin is evenly 
rounded; the ventral margin is straight in the left valve, slightly concave in the right. 
The posterior margin is obliquely rounded and has five spines. 

Ornamentation is restricted to the posterior half of the carapace and consists of 
some 6-8 sulca. These are mainly short, except for the central one which reaches 
to the centre of the carapace. Within this long sulcus is a fine threadlike ridge. No 
internal details could be seen. 

DIMENSIONS: Carapaces 


ie H L/H Ww 
Female 0:83 0-49 I-69 0°43 
Male 0-84 0°47 I-79 0°42 


Discussion: This is similar to C. sagri Deltel (Morphotypes C, D and F), but differs 
from these in L/H ratio as well as ornamentation. C. posticalis Triebel has a com- 
pletely different shape; C. perita Deltel differs in shape, L/H ratio, ornamentation, 
and has only four posterior spines. 


Cytheretta perita Deltel 
(Pl. 19, fig. 8) 
1964 Cytheretta perita Deltel, p. 155, pl. 3, figs 53-55. 
DIAGNOSIS AND DESCRIPTION: The female is triangular in lateral view. There are 


some eight anterior denticles and four posterior spines. Ornamentation is restricted 
to the posterior, where there are six short ridges. 


MATERIAL: I0 valves and carapace from Lespontes. Io 4089. 
TYPE LOCALITY: Coupe de Lespontes, Peyrehorade; Bartonian. 


OF NORTH-WEST EUROPE 337 


STRATIGRAPHICAL RANGE AND DISTRIBUTION: Coupe de Lespontes (Moulin de 
Basat; Ferme Le Vigneau). 
DIMENSIONS: Carapace 
16 H L/H Ww 
Female 0-81 0°43 1-88 0°35 


Discussion: This differs from C. posticalis Triebel in shape, size, inner margin, and 
in having stronger posterior ridges. See also C. postornata sp. nov. 


Cytheretta sculpta Ducasse 
(Pl. 20, figs 9, 10) 
1964 Cytheretta sculpta Ducasse, p. 225, pl. 1, figs 2-4. 


Diacnosis: A species of Cytheretta with a prominent anterior hinge ear in the left 
valve. The ornamentation consists of eleven longitudinal ridges with faint cross- 
ridges between them. 


MATERIAL: 9 carapaces. Io 4090-01, Argiles a Algues, Blaignan. 
TYPE LOCALITY AND HORIZON: Villeneuve-de-Blaye, Eocéne supérieur. 


STRATIGRAPHICAL RANGE AND DISTRIBUTION: Upper Eocene and Sannoisian of the 
Bordeaux region. 


DESCRIPTION: Sexual dimorphism is distinct, the males being more elongate. The 
dorsal margin of the left valve is slightly convex with a prominent anterior hinge ear. 
The anterior margin is obliquely rounded; the ventral margin is slightly concave; 
the posterior margin is evenly rounded. The right valve has a more typical Cyther- 
etta shape due to the lack of the anterior hinge ear. There are some twelve denticles 
along the whole of the anterior margin and four spines along the posterior margin; 
these are present in both valves. The carapace is tapered towards the anterior end 
in dorsal view. 

The ornamentation consists of eleven longitudinal ridges; nos. 2, 4, 7 and 10 run 
the whole length of the carapace; no. 1 forms the dorsal margin and in the left valve 
curves sharply downwards by the hinge ear to join no. 2. No. 3 is faint; no. 5 joins 
no. 4 just before the anterior margin; no. 6 is faint; no. g joins no. 8 in the centre. 
Another ridge is present just below the hinge ear of the left valve. There is a strong 
anterior marginal rim. Between the ridges are faint cross-ridges. There is no sub- 
central plexus. 

No internal features could be seen. The antero-dorsal lobe of the hinge is very 
strong. 


DIMENSIONS: Carapaces 


Y, R L/H Ww 
Female 0-70 0:40 1°75 0°33 
Male 0°73 0:38 I-92 0°33 


Discussion: The ornamentation is unlike that of any other described species of 
Cytheretta. 


338 MID-TERTIARY CYTHERETTINAE 


Cytheretta sp. A 
(PIS GO fies 11) 
MATERIAL: I carapace. lo 4092. 


LOCALITY AND HORIZON: Moiselles; Sables de Beauchamp. 


DIMENSIONS: 
Left valve, male: L, 0:74; H, 0-39; L/H, x-90. 


Discussion: This is very similar to C. ruelensis sp. nov.; the ridge pattern is the 
same, but the ridges are all of about equal strength. This is probably an individual 
of a species ancestral to C. ruelensis. 


Cytheretta sp. B 
(Pl. 9; fig22) 


MATERIAL: 2 broken right valves, 2 distorted carapaces. Io 4093. 


LOCALITY AND HORIZON: Biarritz: Couches a Pentacrinus de la Cote des Basques 
(RO 254; RO 255); Couches des Bains (RO 258). 


DESCRIPTION: This has a posterior hinge ear in the left valve and four posterior 
spines. The ornamentation consists of eleven longitudinal ridges, one of which forms 
the dorsal margin; ridge no. 6 is short, not reaching to the anterior half of the valve. 
There is a strong anterior marginal rim and a wide anterior area of reticulation. A 
weak reticulation is present between the longitudinal ridges. 

DIMENSIONS: 

Right valve: L, 0-75; H, 0:39; L/H, 1-92. 


Discussion: This is of interest as the only Cytheretta sp. found in the Couches a 
Pentacrinus. There are no other species with which it can be compared. 


Cytheretta sp. C 
(Pl. 3, fig. 10) 
MATERIAL: I right valve, L, 0-70. 


LOCALITY AND HORIZON: Sables d’Auvers, Auvers-sur-Oise. 


Discussion: The ornamentation of this valve is very similar to that of C. bambrug- 
gensis Keij, but it differs from the latter in having its greatest height situated more 
to the posterior. The specimen was unfortunately destroyed while being photo- 
graphed with the electron scanning microscope, but is left here for the record. 


Genus FLEXUS Neviani 1928 


1928 Flexus, Neviani, p. 26. 
1958 Eucytheretta Puri, p. 188. 


TYPE SPECIES: Cythere plicata von Munster. 


OF NORTH-WEST EUROPE 339 


DraGnosis: Similar to Cytheretta but with the development of three prominent 
longitudinal ridges. Ornamentation between the ridges varies. The carapace tends 
to be more elongate than Cytheretta. 


Discussion: See Introduction. 


Flexus plicatus (von Munster) 
(Pli22. tiger) 


1830 Cytheve plicata von Munster, p. 63. 

1838 Cythere plicata von Munster, Roemer, p. 518, pl. 6, fig. 26. 

1850 Cypridina plicata (von Munster), Ruess, p. 83, pl. 10, fig. 21. 
1896 Cythere plicata von Munster, Lienenklaus, p. 141. 

1952 Cytheretta plicata (von Munster), Triebel, p. 28, pl. 5, figs 34-35. 
1956 Cytheretta plicata (von Munster), Oertli, p. 65, pl. 8, fig. 194. 
1958 Eucytheretta plicata (von Munster), Puri, p. 188, pl. 3, figs 1-6. 


TYPE LOCALITY AND HORIZON: Astrup, near Osnabruck; Upper Oligocene. 
MATERIAL: 2 carapaces from Astrup. Io 4094. 


STRATIGRAPHICAL RANGE AND DISTRIBUTION: F’. plicatus has been recorded from a 
great variety of localities and horizons. Authenticated occurrences however seem to 
be restricted to the Upper Oligocene of Astrup and Doberg. 


Discussion: This occurs together with a form resembling F. concinnus (Triebel) ; 
samples from the Upper Oligocene of Bithl near Weimer (Kassel) contain only the 
latter. This is the form figured and described by Speyer (1863, pl. 4, fig. 2) and men- 
tioned by Lienenklaus (1894, p. 198). 


Flexus concinnus (Triebel) 
(BiP22Mfigs2) 355) 


1852 Cythere plicata Bosquet (pars) (non von Miinster), p. 60, pl. 2, fig. 13. 
1895 Cythere plicata Lienenklaus (non von Minster), p. 17. 

1905 Cythereis tlicata Lienenklaus (non von Miinster), p. 37, 64. 

1952 Cytheretta concinna Triebel, p. 27, pl. 5, figs 31-33. 

1957 Cytheretta concinna Keij, p. 132, pl. 10, fig. 6. 


MATERIAL: Alzey: 10 valves; Auvers-St-George: 3. lo 4095-97. 
TYPE LOCALITY AND HORIZON: Welschberg; Unterer Meeressand. 


STRATIGRAPHICAL RANGE AND DISTRIBUTION: Unterer Meeressand of the Mainz 
Basin; Stampian of Jeurre, Auvers-St.-George, and Morigny in the Paris Basin; 
Sables de Berg and Argiles a N. comta, Belgium (Sables de Wemmel and Argiles 
d’Asche, Belgium ?). 


F 


340 MID-TERTIARY CYTHERETTINAE 


Flexus gutzwilleri (Oertli) 
(Pl. 22, fig: 4) 
1956 Cytheretta gutzwilleri Oertli, p. 64, pl. 8, figs 189-192. 
MATERIAL: 31 valves and carapaces from the topmost Couches du Phare (RO 270, 
271). Io 4098-99. 


TYPE LOCALITY AND HORIZON: Therwil (near Basel); Cyrenenmergel (Lower 
Chattian). 


STRATIGRAPHICAL RANGE AND DISTRIBUTION: Lower Chattian of Therwil; Couches 
du Phare, Biarritz. 


Flexus solentensis sp. nov. 


DERIVATION OF NAME: After the Solent. 


Diacnosis: A small species of the genus Flexus with a thick anterior marginal rim 
and thick longitudinal ridges. 
Two subspecies have been recognized. 


Flexus solentensis solentensis subsp. nov. 
(Pl. 23, figs 7-10; Text-fig. 30) 


1957 Cytheretta gracilicosta Keij (non Reuss), p. 135, pl. 10, fig. 5. 
1968 Cytheretta gracilicosta Haskins (non Reuss), p. 166, pl. 3, figs 1—10. 


HototyPeE: Io 4100, a female left valve. 
PARATYPES: Io 4101-2. 


MATERIAL: Barton: EBA 1 (Bed F), 4 valves; EHC 2 (Bed D), 2 carapaces. 
Alum Bay: Middle Barton Beds, 5 valves and carapaces. 


TYPE LOCALITY AND HORIZON: Barton; Middle Barton Beds, Bed F. 


STRATIGRAPHICAL RANGE AND DISTRIBUTION: Middle Barton Beds of Barton and 
Alum Bay. 


DIAGNOSIS AND DESCRIPTION: Sexual dimorphism is distinct; sex ratio, I : 3 
The left valve has a strong posterior hinge ear and a very weak anterior one; the 


Fic. 30. Flexus solentensis solentensis; female left valve; X75. 


OF NORTH-WEST EUROPE 341 


dorsal margin is convex. The anterior margin is almost evenly rounded; the ventral 
margin is concave, particularly in the right valve. The posterior margin is obliquely 
rounded. In dorsal view all three ridges can be seen, giving the carapace a tapered 
appearance with the apex at the anterior. 

Ornamentation consists of three longitudinal ridges which end against a thick 
anterior marginal rim. The dorsal ridge forms the dorsal margin between the two 
hinge ears, curving downwards just to the posterior of the anterior hinge ear. The 
median ridge is roughly parallel to the dorsal ridge, but with a less accentuated course. 
The ventral ridge is almost straight. At the posterior the ventral ridge joins the 
median one and this remaining thin ridge then joins the thin posterior part of the 
dorsal ridge. Between the ridges is a coarse reticulation of irregular cross-ridges. 

The hinge of the left valve has a small swollen, but very prominent, antero-dorsal 
lobe; the antero-ventral lobe is small; the antero-median tooth is large and the 
postero-median swelling is almost as big. In the right valve the anterior margin is 
pointed and the posterior tooth is almost equal in size. The inner margin does not 
appear to have a very well developed anterior indentation; the ventral and posterior 
indentations are narrow and deep. The median and posterior segments form a 
continuous steep curve, going a long way towards the dorsal margin. 

There are 24 anterior, 22 posterior and 20 ventral radial pore canals. The selvage 
is prominent; there is a flange groove along the anterior, posterior and ventral 
margins; a list is developed in the antero-ventral and postero-ventral areas. 


DIMENSIONS: 
Left valve Right valve 
1B H L/H WwW iD H L/H 
Female 0°52 0-31 1-68 0°25 0-51 0:27 1-89 
Male 0°54 0:28 1:93 — — _- — 


Flexus solentensis congestus subsp. nov. 
(Pl. 23, figs 11-15) 

DERIVATION OF NAME: Latin—congestus, dense, thick; refers to the longitudinal 
ridges. 

Ho.otyPe: Io 4103, a female left valve. 

PARATYPES: lo 4104-5. 

MATERIAL: EBA 4, 7 valves and carapaces (5 females, 2 males). 

TYPE LOCALITY AND HORIZON: Barton; Upper Barton Beds (Chama Bed, H). 

STRATIGRAPHICAL RANGE AND DISTRIBUTION: So far only known from the type 
locality and horizon. 

DIAGNOSIS AND DESCRIPTION: Shape and internal features are as for the nominate 
subspecies. The ornamentation consists of three very thick ridges which merge into 


a thick anterior marginal rim. The ridges are thicker than the intervening areas; 
the latter have a fine, uneven reticulation. 


Fe 


342 MID-TERTIARY CYTHERETTINAE 


DIMENSIONS: 
Left valve Right valve 
if, H L/H WwW L H L/H 
Female 0-51 0-30 I-70 0:24 0-51 0:25 2°04 
Male 0°54 0:29 1-86 0°25 — a — 


Discussion: The oldest specimens of F. solentensis show similarities to F. ludensis 
sp. nov. in shape, size and ornamentation. In detail, however, the ridges are thicker 
and the reticulation between them consists of cross-ridges rather than the uneven 
reticulation of F. Judensis. They are quite probably related species however. In 
younger beds the ridges thicken until in the Upper Barton Beds the end member of 
the series is met with and is here distinguished as a separate subspecies, F. solentensis 
congestus. The remainder of the Barton Clay has not yielded any ostracods. The 
overlying Brockenhurst Beds contain a form of F. Judensis which must have migrated 
into the area with the Headon Beds transgression. 

F’. gracilicostus (Reuss) shows similarities to F. solentensis and F. ludensis, but has 
much finer ridges and a smaller and more even reticulation between them. In dorsal 
view it is more ovate and the three ridges do not stand out as in F. solentensis and 
F. ludensis. F. gracilicostus is also much larger. 


Flexus ludensis sp. nov. 
(Pl. 23, figs 1-6, 16) 
DERIVATION OF NAME: After the Marnes a P. ludensis in which it is found. 


DiaGnosis: A small species of the genus Flexus with thick longitudinal ridges; at 
the posterior the dorsal and ventral ridges join the median one; at the anterior the 
ridges join a strong marginal rim. Between the ridges is an uneven reticulation. 
At the posterior are three small spines. 

HototyPeE: Io 4106, a female left valve. 


PARATYPES: Io 4107-12. 


MATERIAL: Verzy: PVY 2, 8 valves and carapaces; PVY 4, 22. Chavencon: 
PCC 2, 9 valves and carapaces. Whitecliff Bay: EWB(A), 2 valves and carapaces; 
EWB(B), 3; EWB 19, 2; EWB 22,1. Headon Hill: EHH 42, 4 valves and carapaces. 

TYPE LOCALITY AND HORIZON: Verzy; Marnes a P. ludensis. 


STRATIGRAPHICAL RANGE AND DISTRIBUTION: Marnes a P. ludensis of Verzy and 


Chavengon. Brockenhurst Beds, Whitecliff Bay; Middle Headon Beds, Headon Hill, 
Whitecliff Bay. 


DESCRIPTION: Sexual dimorphism is pronounced; sex ratio, I : 2:5. The left 
valve has a strong posterior hinge ear and a weak anterior one; the dorsal margin is 
convex. The anterior margin is almost evenly rounded with a few marginal denticles 
in the ventral portion. The ventral margin is straight in the anterior half, curving 
round into the posterior margin in the posterior half. The posterior margin is 
obliquely rounded and has three small spines in the median portion. The right valve 


OF NORTH-WEST EUROPE 343 


has a concave ventral margin. In dorsal view all three ridges can be clearly seen, 
giving the carapace a tapered appearance with the apex at the anterior. 

Ornamentation consists of three strong, prominent longitudinal ridges which end 
against a strong anterior marginal rim. The dorsal ridge forms the dorsal margin 
between the two hinge ears; it curves sharply downwards just to the posterior of the 
anterior hinge ear. The median ridge is slightly sinuous, running roughly parallel 
to the dorsal ridge but with a less accentuated course; it is very faint in the extreme 
posterior, but can be traced right to the margin, just before which it bifurcates. The 
ventral ridge is almost straight, curving upwards just before reaching the anterior 
marginalrim. All the ridges are faint at the posterior and tend to disappear amongst 
the reticulation, but the dorsal and ventral ridges appear to join the median ridge. 
The anterior marginal rim is particularly strong in the right valve. Between the 
ridges is an uneven reticulation; there is a particularly prominent “ridge’’ running 
between the median and dorsal ridges just to the posterior of centre. The specimens 
from the Headon Beds lack this “‘ridge’’. The area between the dorsal ridge and the 
antero-dorsal angle is almost smooth. 

The hinge of the left valve has a swollen antero-dorsal lobe, prominent antero- 
ventral lobe, large antero-median tooth and a small postero-median swelling. In the 
right valve the posterior and anterior teeth are about equal in size and rather small. 
The selvage is prominent, with a small anterior and posterior flange groove and wide 
ventral one; the flange is particularly prominent along the anterior margin. A list is 
strongly developed in the antero-ventral and postero-ventral regions. No other 
internal details could be clearly seen. 


DIMENSIONS: 
Left valve Right valve 
ip H L/H Ww 1 H L/H 
Female 0:50 0:30 1:67 0:23 0°51 0:26 1:96 
Male 0°52 0:28 1-86 0:24 0°51 0:25 2°04 


Discussion: The specimens from the Headon Beds are slightly different from the 
Ludian ones, particularly with the reticulation between the ridges. The similarities 
are so strong, however, that it was thought unjustifiable to separate them. See also 
F. solentensis sp. nov. 


Flexus lenijugum sp. nov. 
(Pl. 21, figs 7, 9; Pl. 22, figs 9, 10) 
DERIVATION OF NAME: Latin—lenis, smooth; jugum, ridge. Refers to the orna- 
mentation. 


D1aenosis: A species of Cytheretta with an almost straight posterior margin bearing 
four spines ; apart from the longitudinal ridges the carapace is smooth. 


Hototype: Io 4113, a female left valve. 
PARATYPE: Io 4114. 
MATERIAL: 8 carapaces. 


344 MID-TERTIARY CYTHERETTINAE 


TYPE LOCALITY AND HORIZON: Chateau Romefort, Blaignan; Argiles a algues. 


STRATIGRAPHICAL RANGE AND DISTRIBUTION: So far only known from the type 
locality. 


DESCRIPTION: Sexual dimorphism can be discerned, but it is not very prominent. 
There are anterior and posterior hinge ears 1n the left valve; the dorsal margin is 
evenly rounded; the ventral margin is slightly concave in the left valve and strongly 
so in the right; the posterior margin is almost straight and has four spines. It is 
tapered towards the anterior in dorsal view. 

The ornamentation consists principally of three longitudinal ridges. The dorsal 
ridge forms the dorsal margin; in the right valve it is continuous with the anterior 
margin rim; in the left, it ends beneath the anterior hinge ear. The median ridge is 
short and has another weak ridge above it in the posterior. The ventral ridge is 
strong, joining the anterior marginal rim and, at the posterior, the weak ridge above 
the median ridge. The anterior marginal rim is strong, running from the anterior 
hinge ear to the ventral margin. 

No internal features could be seen. 


DIMENSIONS: Carapaces 


18 H L/H Ww 
Female 0-80 0°43 1-86 0:38 
Male 0-80 0-41 1:95 0:37 


Discussion: F. lenijugum resembles F. plicatus (von Minster) with the lack of 
ornamentation between the longitudinal ridges. It differs in shape; FP. plicatus has a 
more tapered posterior margin in lateral view. It also differs in the configuration of 
the ridges; the dorsal ridge does not form the dorsal margin in F. plicatus, nor does it 
join the anterior marginal rim; the ventral ridge is continuous with the anterior 
marginal rim, not merely joining it. F. lenijugum differs from all other described 
species by the absence of ornamentation between the ridges. 


Flexus schoelleri (Keij) 
(Pl. 22, figs 6-8) 


1955 Pavracytheretta schoellert Keij, p. 119, pl. 16, fig. 4; pl. 19, figs 11-12. 
1956 Cytheretta schoelleri (Keij) Oertli, p. 65, pl. 8, figs 196-197. 

1965 Protocytheretta schoellert (Keij) Moyes, p. 56, pl. 6, fig. 13. 

1969 Protocytheretta schoelleri (Keij) Carbonnel, p. 111, pl. 8, figs 1-3. 


MATERIAL: Couches du Phare: RO 269, 10 valves and carapaces; RO 270, 5; RO 
271, 3. Io 4115-7. St. Geours-de-Maremne: ASG I, 3 valves and carapaces; 
ASG 252 eNSGr3y 2: 

TYPE LOCALITY AND HORIZON: Moulin de Gamachot, Upper Aquitanian (?). 

STRATIGRAPHICAL RANGE AND DISTRIBUTION: Couches du Phare, Biarritz; Faluns 


Bleues, St. Geours-de-Maremne; Aquitanian and Burdigalian of the Bordelais and 
Rhone. 


OF NORTH-WEST EUROPE 345 


Discussion: This was placed by Puri (1958) into his new genus Protocytheretta, 
defined as ‘Cytheretta’-shaped, but with three longitudinal ridges; Flexus was 
regarded as being ‘Cythereis’ shaped and with three longitudinal ridges. F. schoel- 
lert has a truncated posterior margin which is not at all ‘Cytheretta’-like and the rod- 
like ridges are completely different from those of P. daniana (Brady). (See Hulings 
and Puri, 1964, p. 327 for an illustration of P. daniana.) F. schoelleri is probably not 
related to any other Plexus species here described, but is included in the genus on the 
purely morphological grounds that it has three longitudinal ridges. 

The specimens from the Couches du Phare are smaller than the typical F. schoelleri 
(length of female carapace = 0-60 compared with 0:78). 


Flexus sp. A 
(PlF 22h fie: 5) 


MATERIAL: I carapace. lo 4118. 

LOCALITY AND HORIZON: Bambrugge; Sables de Lede. 

Dimensions: L, 0-64; H, 0:36; W, 0:31; L/H, 1-78. 

Discussion: This is almost certainly a new species, but lack of material prevents a 
description. The configuration of the ridges is similar to FP. concinnus (Triebel), but 
its shape is different from the latter both in dorsal and in lateral view, and it has a 
much stronger anterior marginal rim. 


XV. CONCLUSIONS 


The Cytherettinae have proven useful for helping to establish a correlation between 
the various localities in the Anglo-Paris-Belgian area in the Eocene and between this 
region and Germany in the Oligocene. In particular they support the idea of cor- 
relating the Sables de Lede with the Upper Lutetian of the Paris Basin, placing the 
Sables moyens in the Middle Eocene and correlating them with the Upper Brackle- 
sham Beds of Hampshire, and correlating the Barton Beds with the Marnes a 
P. ludensis. Unfortunately the Cytherettinae provide little information concerning 
the relationship of the type Lattorfian with other areas of western Europe. The four 
species recorded from the Headon Beds suggest a relationship with the Bartonian on 
the one hand (C. porosacosta, F. ludensis) and with the Oligocene on the other 
(C. headonensis, C. aff. stigmosa), although the latter are related to the Eocene 
C. carita and C. cellulosa. Other ostracods however support a Bartonian age for 
the Headon Beds (Keen, 1968). Detailed correlation between England, France, 
and Belgium is possible using the evolution of C. costellata and C. laticosta. 

The Aquitaine Basin formed a very distinct province, the only group in common 
with the northern areas being the C. eocaenica group. This suggests that the English 
Channel as now known could hardly have existed during the Eocene and Oligocene. 

The presence of the Cytherettinae in Tertiary sediments is a good indication of 
shallow marine conditions, close to shore. Of the main species groups present, only 
the superspecies C. laticosta seems to have preferred muddy waters. The C. haimeana 
group were most abundant in clear waters in which calcareous or sandy sediments 


346 MID-TERTIARY CYTHERETTINAE 


were accumulating, the C. eocaenica, C. tenuipunctata, C. rhenana, and C. sagri 
groups inhabited clear waters where sands were being deposited. 


REFERENCES 


AsissIn, M. 1955. See Girard d’Albissin, 1955. 

ANDERSON, F. W. 1964. ‘The law of ostracod growth. Palaeontology, London 7 : 85-104. 

APOSTOLESCU, V. 1955. Description de quelques ostracodes du Lutetien du Bassin de Paris. 

Cah. géol. Thoiry, 28/29 : 241-279, pls. 1-8. 

1956. Contribution a l'étude des ostracodes de |’Eocene infeérieur (s.l1.) du Bassin de Paris. 

Rev. Inst. franc., Petvole, Paris 11 : 1327-1352, pls. 1-4. 

1964. Repartition stratigraphique generale des Ostracodes du Paleogene des bassins de 

Paris et de Bruxelles. In colloque sur le Paleogene, Bordeaux, 1962. Mém. Bur. Rech. 
géol. min., Paris, 28 : t.II, 1035-1040. 

Ascout, P., 1965. Ecological study on Ostracoda from bottom cores of the Adriatic Sea. 
Pubbl. Staz. zool. Napoli, 33 (suppl) : 213-246, 4 pls. 

Bates, D. A. J. 1958. Foraminifera of the Oligocene of Belgium. Imst. Roy. Sci. Nat. 
Belgique, Bruxelles 143 : 188p., 13 pls. 

Benson, R. H. 10965. In discussion of Sandberg, 1965, p. 510. 

Benson, R. H. & CoLEMAN, G. L. 1963. MJRecent marine ostracodes from the eastern Gulf of 
Mexico. Paleont. Contr. Univ. Kansas., Arthropoda, Art. 2 : 1-52, 8 pls. 

Benson, R. H. & Mappocks, R. F. 1964. Recent ostracodes of Knysna Estuary, Cape 
Province, Union of South Africa. Paleont. Conty. Univ. Kansas., Anthropoda, Art. 5 : 1-39, 
6 pls. 

Bop, VAN Den, W. A. 1957. Ostracoda from the Paleocene of Trinidad. Muicropaleontology, 
New York 3 : 1-14, pl. 1-4. 

BosguEt, J., 1952. Description des entomostraces fossiles des terrains Tertiaires de la France 
et de la Belgique. Mém. cour. Acad. vr. Sci. Belg., Bruxelles, 24 : 142 p., 6 pls. 

Bowen, R.W.C. 1953. Ostracoda from the London Clay. Proc. Geol. Ass. Lond., 64 : 276— 
292, 8 text figs. 

Brapy, G.S. 1868. La cote de Syrie; In: De Folin, L., and Perier, L., Les fonds de la mer, 

legbars) i 3 fore, 1, 12 jo), 

Brapy, G. S., CrosskEy, H. W. & Ropertson, D. 1874. A monograph of the post-Tertiary 
entomostraca of Scotland, including species from England and Ireland. Palaeontogr. Soc. 
(Monogr.) London: 232 p., 16 pls. 

CAPELLI, G. B. 1905. Contribuzione allo studio degli Ostracodi fossili dello strato a sabbie 
grigie della Farnesina presso Roma. Boll. Soc. geol. ital., Roma 24 : 303-343, pl. 9-10. 
CARBONNEL, G. 1969. Les ostracodes du Miocene Rhodanien. Docum. Lab. Géol. Fac. Sci. 

Lyon, 32 : 469 p., 16 pls. 
CAVELIER, C. 1964. L’Oligocene inférieur du bassin de Paris. In Colloque sur le Paleogene, 
Bordeaux, 1962. Mém. Bur. Rech. géol. min., Paris 28 : t.I, 65-73. 
1965. Le Sannoisien de Sannois (Seine-et-Oise) dans le cadre du bassin de Paris et sa 

signification stratigraphique. Bull. Soc. géol. Fr., Paris (7) 7 : 228-238. 

Curry, D. 1965. The Palaeogene Beds of South-east England. Proc. Geol. Ass. Lond. 76: 

151-174. 

1966. Problems of correlation in the Anglo-Paris-Belgian Basin. Proc. Geol. Ass. Lond. 

77 : 437-467. 

Curtis, D. M. 1960. Relation of environmental energy levels and ostracod biofacies in east 
Mississippi Delta area. Bull. Am. Ass. Petvol. Geol., Chicago 44 : 471-494. 

CusuMan, J. A. 1906. Marine Ostracoda of Vineyard Sound and adjacent waters. Proc. 
Boston Soc. nat. Hist., Boston 32 : 359-385, pls. 27-38. 

DELTEL, B. 1961. Les ostracodes du Paleogene moyen et supérieur d’Aquitaine meridionale. 
These 3em Cycle, Bordeaux., No. 95 : 215 p., 19 pls. 


OF NORTH-WEST EUROPE 347 


DELTEL, B. 1964a. Ostracodes du Paleogene d’Aquitaine meridionale. In Colloque 
sur le Paleogene, Bordeaux, 1962. Mém. Bur. Rech. géol. min., Paris, 28: t.II, 

2041-2048. 

1964b. Nouveaux ostracodes de l’Eocene et de l’Oligocene de l’Aquitaine meridionale. 
Act. Soc. Linn. Bordeaux, 100 (for 1962-63) 127—221,: 6pls. 

DeErRoo, G. 1966. Cytheracea (Ostracodes) du Maastrichtien de Maastricht (Pays-Bas) et des 
regions voisines; resultats stratigraphique et paleontologiques. Meded. geol. Sticht., 
s’Gravenhage, Ser. C., 2, no. 2: 197 p., 27 pls. 

DrooGER, C. W., KAAsscHIETER, J. P. H. & Kety, A. J. 1955. The microfauna of the Aqui- 
tainian-Burdigalian of south-western France. Ver. Ned. Ak. Wet. Nat., Deel, 21, no. 2: 
135 p., 20 pls. 

DucassE, O. 1964. Quelques espéces nouvelles d’ostracodes de l’Eocene terminal Girondin. 
Act. Soc. Linn. Bordeaux, 100 (for 1962-63) : 223-248, 3 pls. 

EaGcar, S. H. 1965. Ostracoda of the London Clay (Ypresian) in the London Basin : 1. 
Reading district. Revue Micropaléont., Paris, 8 : 15-32, 2 pls. 

Garcia, E. R., DE. 1969. Amendment a la sub-famille Cytherettinae Triebel 1952 (famille 
Cytherettidae (Triebel) Howe 1961. Proc. 3rd African Micvopal. Coll. (Cairo 1967), Cairo: 
217-223, 2 pls. 

GIRARD D’ALBISSIN, N. 1955. Etude du Sannoisien de Ile-de-France. Awnns. Cent. Etud. 
Docum. paléont., Paris, no. 11: 

Haskins, C. W. 1968. Tertiary Ostracoda from the Isle of Wight and Barton, Hampshire, 
England. Revue Micropaléont., Paris, 11 : 161-175, 3 pls. 

Hazet, J. E., 1967. Classification and distribution of Recent Hemicytheridae and Trachyle- 
beridae (Ostracoda) off northeastern North America. Geol. Surv. U.S. Prof. Paper, Washing- 
ton, 564 : 49 p., 2 figs., 11 pls. 

Hutines, N.C. & Puri, H.S. 1965. The ecology of shallow water ostracods off the west coast 
of Florida. Pubbl. Staz. zool. Napoli, 33 (suppl.) : 308-344. 

Jones, T. R. 1856a. Notes on the Entomostraca of the Headon and Osborn Series. Mem. 

Geol. Surv. G.B., London, (Forbes 1856) : p. 157. 

1856b. A monograph of the Tertiary Entomostraca. Palaeontogy. Soc. (Monogr.), 

London : 68 p., 6 pls. 

1870. Notesonthe Tertiary EntomostracaofEngland. Geol. Mag., London, 7 : 155-159. 

Jones, T. R. & SHERBORN, C. D. 1889. A supplemental monograph of the Tertiary Ento- 
mostraca of England. Palaeontogr. Soc. (Monogr.), London : 55 p., 3 pls. 

Keen, M.C. 1968. Ostracodes de l’Eocene supérieur et l’Oligocene inferieur dans les bassins 
de Paris, du Hampshire et de la Belgique et leur contribution a |’échelle stratigraphique. 
In Colloque sur l’Eocene, Paris, 1968. Mém. Bur. Rech. géol. min., Paris, 58 : t.1, 137-145. 

Kez, A. J. 1955. See Drooger ef al., 1955. 

1957. Eocene and Oligocene Ostracoda of Belgium. Mem. Inst. Roy. Sci. Nat. Belgique, 

Bruxelles, 136 : 210 p., 23 pls. 

Kornicker, L.S. 1965. Ecology of Ostracoda in the north-western part of the Great Bahama 
Bank. Pubbl. Staz. zool. Napoli, 33 (suppl) : 345-360. 

Kruit, C. 1955. Sediments of the Rhone Delta. I. Grain size and microfauna. Ver. Ned. 
Geol. Gen., Deel, 15 : 359-499, 6 pls. 

Kuiper, W. N. 1918. Oligocine und Miocaine Ostrakoden aus den Niederlanden. Thesis, 
Groningen : 90 p., 3 pls. 

LatHam, M. H. 1938. Some Eocene Ostracoda from North-West India. Proc. R. Soc. 
Edinb. 59 : 38-48. 

LIENENKLAUS E. 1894. Monographie der Ostrakoden des nordwestdeutschen Tertiars. 

Z. dt. geol. Ges., Berlin, 46 : 158-268, pl. 13-18. 

1895. Die Ostrakoden des Mitteloligociins von Jeurre bei Estampes. Verh. naturh. Ver. 
preuss. Rheintl., Bonn, 10 : 125-156, 3 pls. 
1896. Ostracoda; in Kisstinc, E. : Die fauna des Mitteloligocans im Berner Jura. 

Abh. schwz. pal, Ges. Basel 22 : 22-33, pl. 2. 


348 MID-TERTIARY CYTHERETTINAE 


LIENENKLAUS, E. 1905. Die Ostrakoden des Mainzer Tertiar-Beckens. Ber. senck. natf. 
Ges., Berlin, 1904/5 : 3-74, 4 pls. 
MARLIERE, R. 1958. Ostracodes du Montien de Mons et resultats de leur étude. Mém. Soc. 
Belg. géol. Bruxelles 5 : 1-53, pl. 1-6. 
MeuEs, G. 1941. Die Ostracoden der Oberoligozans der Umgebung von Budapest. Geol. 
hung. pal., Budapest 16 : 1-96, pl. 1-5. 
MorkKHOoVEN, F. P. C. M. van. 1962. Post-Palaeozoic Ostracoda. Their morphology, 
taxonomy, and economic use. Elsevier, Amsterdam 1 : 204 p. 
1963. Post-Palaeozoic Ostracoda. Elsevier, Amsterdam 2 : 478 p. 
Moyes, J, 1965. Les ostracodes du Miocene Aquitain. Thesis, Bordeaux: 338 p., 
13 pls. 
Mutier, G. W. 1894. Ostracoden des Golfes von Neapel und der angrensenden Meere- 
sabschnitte. Fauna u Flova Neapel, Berlin : 21 : 403 p., 40 pls. 
1912. ‘Ostracoda’, Das Tierreich, Berlin, 31 : 1-434, 92 pls. 
Munster, G. von. 1830. Uber einige fossile Arten Cypris und Cythere. Neues Jb. Miner. 
Geol. Palaont., Stuttgart,1 : 60-67. 
Namias, I. 1900. Ostracodi fossili della Farnesina e Monte Mario presso Roma. Palaeontogr. 
italica, Pisa 6 : 79-114, pl. 14-15. 
Neviani, A. 1928a. Ostracodi fossili d’Italia. I” Vallebiaja Calabriano. Memorie Accad. 
pont. Nuouri Lincei, Roma, 11 : 1-120, 2 pls. 
1928b. Oialcuni Ostracodi raccolti sulle spiaggie di Barie di Rimini. <Adti. Accad. pont. 
Nuoumi Lincet, Roma 81 : 123-132, 3 figs. 
OeErRTLI,H. 1956. Ostrakoden aus der Oligozénen und Miozanen Molass eder Schweiz. Schweiz 
Pal. Abh., Basel, 74 : 119 p., 16 pls. 
1965. In discussion of General Problems of ecology and Palaeoecology. Pubbl. Staz. 
zool. Napoli, 33 (suppl) : 538-9. 
PoMEROL,C. 1964. Le Bartonien du bassin de Paris. In Colloque sur le Paleogene, Bordeaux, 
1962. Mém. Bur. Rech. géol. min., Paris 28 : t.I, 153-168. 
Puri, H. S. 1952. Ostracode genera Cytheretta and Paracytheretta in America. J. Paleont., 
Tulsa, Okla. 26 : 199-212, pl. 39, 40. 
1958. Ostracode subfamily Cytherettinae. Florida Geol. Surv. Geol. Buil., Tallahasse 
40 : 183-194, pls. I-3. 
Puri, H. S. & Hutines, N. C. 1957. Recent ostracod facies from Panama City to Florida 
Bay. Tvans. Gulf-Cst. Ass. geol. Soc., New Orleans, 7 : 167-190. 
Puri, H.S., Bonapuce, G. & MaLLoy, J. 1965. Ecology of the Gulf of Naples. Pubbl. Staz. 
zool. Napoli. 33 (suppl) 33 : 87-199, 67 figs. 
Reuss, A. E. 1850. Due fossilen Entomostracaen des osterreichischen Tertiarbeckens. 
Naturw. Abh, Berlin, 1 : 41-92, pl. 8-11. 
1851. Uber die fossilen Foraminiferen und Entomostraceen der Septarienthone der 
Umgebung von Berlin. Z. dt. geol. Ges., Berlin, 3 : 49-92, pls. 3-7. 
1853. Einige Foraminiferen Bryozoen und Entomostraceen des Mainzer Beckens. 
Neues Jb. Miner. Abh. geol. u. Pet., Stuttgart, 21 : 670-679, pl. 9. 
1855. Ein Beitrag zur genaueren Kenntniss der Kreidegebilde Mecklenburgs. Z. dt. 
geol. Ges., Berlin 7 : 261-292, pls. 8-11. 
1869. Zur fossilen kauna der Oligozénschichten von Gaas. Sitz.-Ber. k. Akad. Wiss. 
math.-naturw. Cl., Wien, 57; 480-486, pls. 5-6. 
RoEMER, F. 1838. Die Cytherinen des Molasse Gebirges. Neues Jb. Miner. geol. u. Pall., 
Stuttgart 6 : 514-510, pls. 5-6. 
Rome, Dom. R. 1964. Ostracodes des environs de Monaco, leur distribution en profondeur, 
nature des fonds marins explores. Pubbl. Staz. zool. Napoli 33 (suppl) : 200-212. 
Ruaaier1, G. 1950. Gli Ostracodi della Sabbie grige quaternarie (Milazziano) di Imola. 
G. Geol. Bologna, ser. 2, 21 : 1-57, pl. 1, 34 figs. 
1953. Eta e faune di un terrazzo marino sulla costa ionica della Calabria. G. Geol. 
Bologna, ser. 2, 23 : 20-144, 6 pls., 3 figs. 


OF NORTH-WEST EUROPE 349 


RuGGIERI, G. 1959. Enumerazione degli Ostracodi marini del Neogene, Quaternario e Recente 
italianid escritti o elencati nell’ultimo decennio. Atti Soc. ital. Sci. nat., Milan 98 :183-208. 
1962. Gli Ostracodi marini del Tortoniano (Miocene modio-superiore) di Enna, nella 

Sicilia Centrale. Palaeontogr. Italica, Roma 56 : 1-68, pls. 11-17, 15 figs. 

SANDBERG, P. A. 1965. Notes on some Tertiary and Recent brackish-water Ostracoda. 
Pubbl. Staz. zool. Napoli 33 (suppl) : 498-514. 

SEQUENZA, G. 1880. Le formazioni tertiarie nella provincia di Reggio (Calabria) Atti Accad. 
naz. Lincet Memorie, Roma 6 : 1-416. 

SPEYER, O. 1863. Die Ostracoden der Casseler Tertiarbildungen. Ber. Ver. Naturk., Cassel 
24 : 1-62, pls. 1-4. 

SKOGSBERG, T. 1928. Studies on marine ostracodes. Part II. External Morphology of the 
genus Cythereis with description of twenty-one new species. Occ. Pap. Calif. Acad. Sci., 
San Francisco, 15 : 1—155, 6 pls. 

SonmMEz, N. 1963. Deux nouveau genres d’Ostracodes du Paleogene de Thrace (Turquie):. 
Revue Micropaléont., Paris,6 : 76-84, 1 pl. 

SONMEZ-GoKCEN, N. 1964. Notice sur le nouvel age determine par les Ostracodes de la serie a 
Congeria du Neogene des environs de Catalca (Thrace). Bull. Miner. Res. Explor. Inst 
Ankara 63 : 47-59. 

STCHEPINSKY, A. 1963. Etude des Ostracodes du Stampien d’Alsace et complement a l’étude 
des ostracodes du Sannoisien d’Alsace. Bull. Serv. Carte géol. Als. Lovr., Strasbourg, 16 : 
151-173. 

STRAUB, E. W. 1952. Mikropalaontologische Untersuchungen Tertiar zwischen Ehingen und 
Ulma.d.donau. Geol. Jb., Stuttgart 66 : 433-524, 3 pls. 

Swain, F. M. 1955. Ostracoda of San Antonio Bay, Texas. J. Palaeontol., Tulsa, Okla. 
29 : 561-646, pl. 59-64. 

1969. Taxonomy and ecology of near-shore Ostracoda from the Pacific coast of North 
and Central America. In The Taxononomy, Morphology, and Ecology of Recent Ostracoda, 
ed. Neale, J. W., Oliver and Boyd, Edinburgh, 423-474, 11 pls. 

SYLVESTER-BRADLEY, P.C. 1951. The subspecies in palaeontology. Geol. Mag., London 88 : 

88-102. 

1962. The taxonomic treatment of phylogenetic patterns in time and space, with 
examples from the Ostracoda. Syst. Assoc. Publ., London 4 : 119-133. 

SZCEZECHURA, J. 1971. Paleocene Ostracoda from Nugssuaq, West Greenland. Meddr. 
Gronland, Kobenhavn, 193 : 42 p., 8 pls. 

TERQquEM, M. O. 1878. Les Foraminiferes et les Entomostraces-Ostracodes du Pliocene de 
V’Ile de Rhodes. Mém. Soc. géol. France, Paris, 3e ser., I : 1-135, 14 pls. 

TRIEBEL, E. 1952. Ostracodem der gattung Cytheretta aus dem Tertiar des Mainzer Beckens. 
Notissbl. Hess. L. Amt. Bodenforsch., Wiesbaden 6 : 15-30, pl. 2-5. 

ViIGNEAUX, M. 1964. Le bassin d’Aquitaine. In Colloque sur le Paleogene, Bordeaux, 1962. 
Mém. Bur. Rech. géol. min., Paris 28 : t.2, 177-220. 

WRIGLEY, A. & Davis, A.G. 1937. The occurrence of Nummulites planulatus in England, with 

a revised correlation of the strata containing it. Proc. Geol. Ass. Lond. 48 : 203-227. 


M. G. KEEN, B.Sc., Ph.D., 
Department of Geology, 
THE UNIVERSITY, 
Griascow, G12 800 


PIC IN ICIS, 
Cytheretta judaea (Brady) 


FIGs I, 4-7, 9. Specimens from Recent beach sand, Rimini. 


Fic. 
Fic. 
Fic. 
Fic. 
Fic. 
Fic. 


Fic. 


a, 


OW DAB 


Left valve, female, lo 3807 x 70, L = 0-75 mm. 
Right valve, male, Io 3792, « 100, L = 0-79 mm. 
Right valve, male, lo 3810, x 70, L = 0-79 mm. 
Left valve, female, lo 3793, x 70, L = 0:75 mm. 
Enlargement of Io 3810 x 140. 

Posterior radial pore canals of Io 3793, x Ioo. 


Cytheretta subradiosa (Roemer) 


Right valve, male. Io 3795 < 100, L = 0-81 mm, Lower Pliocene, Rimini. 


BOE MIN 1 
THE BRITISH MUSEUM (NATURAL HISTORY) 
GEOLOGY Vol 2n Ne: 6 


CORRIGENDA 


Plate 2, caption to Fig. 8 
For “‘punctuation” read “‘punctation’’. 


Plate 15, caption to Fig. 10 
For “Io 4031’ read “Io 4030”. 


Plate 19, caption to Fig. 5-7, 9 
For “‘Calcaire a Algues” read “‘Calcaire 4 Algues’’. 


Bull. By. Mus. nat. Hist. (Geol.) 21, 6 PLATE 1 


FIGs. 


Fic. 
Fic. 
Fic. 
Fic. 
Fic. 
Fic. 
Fic. 
Fic. 
Fic. 
EKG, 1 


IPIL JAIN, 2 


All, except figs. 7, 8, x 70 


I-10 Cytheretta costellata costellata (Roemer) 


OO ON AUNHW DN H 


Fig. 5 from Sables de Lede, Bambrugge; Fig. 6 from Upper Bracklesham 
Beds, Selsey; remainder from Lutetian IV, Damery. All except Fig. 5 
are MORPHOTYPE A. 


Left valve, female, lo 3796, L = 0-69 mm. 

Left valve, male, lo 3798, L = 0-72 mm. 

Right valve, female, lo 3797, L = 0-69 mm. 

Right valve, male, lo 3799, L = 0:72 mm. 

Left valve, female, Io 3802, L=o-72mm. MORPHOTYPE B. 
Left valve, female, lo 3803, L = 0:64 mm. 

Detail of lo 3797, x 140 

Detail of Io 3797 showing “ punctuation ’”’ between the ridges, x 300 
Female carapace, dorsal view, lo 3800, L = 0-70 mm. 

Male carapace, ventral view, Io 3801, L = 0:75 mm. 


Bull. By. Mus. nat. Hist. (Geol.) 21, 6 PLATE 2 


PLATE 3 


All, except Fig. 8, x 75 


Fic. 1-8 Cytheretta costellata grandipora subsp. nov. 


IE, i 
Ine, 2 
Fig. 3 
Fic. 4 
Fig. 5 
Fic. 6 
ING, 97 
EiGe 1S) 
lane, ©) 
aK, WO) 


MORPHOTY PE C, Left valve male, Io 3812, L = 0-83 Auvers-en-Oise. 
MORPHOTYPE, E. Right valve, female, lo 3811, L = 0-74 Auvers-en-Oise. 
MORPHOTYPE, D, Left valve, male, Io 3809, L = 0-83 Auvers-en-Oise. 
MORPHOTYPE, E, Right valve, female, lo 3805, L = 0-77 Moiselles. 
MORPHOTYPE, D, Left valve, female, lo 3808, L = 0-74 Auvers-en-Oise. 
MORPHOTYPE, E, Right valve, male, Io 3807, L = 0-85 Moiselles. 
MORPHOTYPE E, Left valve, female, lo 3804, L = 0-76 Moiselles. 
HOLOTYPE 

Enlargement of Io 3804 showing “ pores ’”’. x 150. 


Cytheretta bambruggensis Keij. Right valve, female, lo 3827, L = 0-74. 
Sables de Lede, Bambrugge. 


Cytheretta sp. C. Right valve, female, L=o-70 Auvers-en-Oise. 
Specimen destroyed. 


Bull. By. Mus. nat. Hist. (Geol.) 21, 6 PLATE 3 


PLATE 4 


2S 7/8) 


Fic. 1-8 Cytheretta costellata cratis subsp. noy. All specimens are MORPHO- 
TYPE F from the Marnes a P. ludensis, Verzy. 


Fig. 1 Left valve, female, Io 3814, L = 0:73 HOLOTYPE 

Fig. 2 Left valve, male, Io 3817, L = 0-76 

Fig. 3 Right valve, female, lo 3815, L = 0-70 

Fig. 4 Right valve, male, Io 3818, L = 0-83 

Fie. 5 Left valve, larval no. 8, Io 3820, L = 0-60 

IMG, © Right valve, larval no. 8, Io 3819, L = 0-60 

Fig. 7 Female carapace, ventral view, Io 3816, L = 0-73 
8 


Male carapace, dorsal view, Io 3821, L = 0-76 


Fic. 9-11 Cytheretta costellata antecalva subsp. nov. All specimens are 
MORPHOTYPE G from the Middle Barton Beds, Barton. 


Fic. 9 Left valve, male, Io 3825, L = 0:84 
Fic. 10 Left valve, female, Io 3823, L = 0-77. HOLOTYPE. 
Fic. 11 Right valve, female, lo 3824, L = 0-77 


Bull. Br. Mus. nat. Hist. (Geol.) 21, 6 PLATE 4 


PILI 
Tic. 1-3 Cytheretta costellata cratis subsp. nov. 


ING, it Right valve, female, Ilo 3822, L = 0-67, x 80, showing the inner margin. 
From the Marnes a P. ludensis, Chavencon. 

Rie 2 Hinge of lo 3822. x 400 

Bie. 3 Central muscle scars and fulcral point of Io 3822. x 800. 


Tlic. 4-7 Cytheretta ruelensis subsp. nov. Io 3837, Sables de Cresnes, Le Ruel. 
x 80. Female carapace. HOLOTYPE. 


ITE, AL Posterior view 
Fig. 5 Dorsal view 
Fic. 6 Left valve 
ErGan7, Right valve 


PLATE 5 


Bull. By. Mus. nat. Hist. (Geol.) 21, 6 


IPILNIDID © 
All x 70 
Fic. 1, 6 Cytheretta haimeana (Bosquet) 
le. it Left valve, female, lo 3834, L = 0-60. Lutetian IV, Damery. 
Fic. 6 Left valve, female, lo 3835, L = 0-70. Sables de Beauchamp, Moiselles. 
Fic. 2,5 Cytheretta crassivenia Apostolescu. 
lie, 2 Left valve, female, Io 3828, L = 0-66. Lutetian IV, Damery. 
Fic. 5 Left valve, female, lo 3829, L = 0-70. Sables de Beauchamp, Moiselles. 


Big. 3 Cytheretta aff. decipiens Keij 
Left valve, female, of a carapace Io 3833, L = 0-66. Marnes a P. ludensis, 
Chavencon. 


Fic. 4,7 Cytheretta ruelensis sp. nov. 


Fig. 4 Ventral view of male carapace, Io 3838, L = 0-85. Sables de Cresnes, 
eskuell 
Fig. 7 Left valve of Io 3838. 


Fic. 8-10 Cytheretta decipiens Keij 
Specimens from Sables de Beauchamp. Moiselles. 


Fie. 8 Left valve, female, Io 3830, L = 0:69 
FIG. 9 Left valve, male, Io 3832, L = 0-81 
FIG. 10 Right valve, female, lo 3831, L = 0-73 


Fic. 11 Cytheretta sp. A 
Left valve, Io 4092, L = 0-74. Sables de Beauchamp, Moiselles. 


PLATE 6 


Bull. By. Mus. nat. Hist. (Geol.) 21. 6 


ee 


oe 


beg A PEV Ps Mase, 
cpa eet er 


PLATE 7 


Cytheretta eocaenica Keij 
EE, © from Lutetian IV, Damery; remainder from Sables de Lede, Bambrugge. 


IEW, Left valve, female, Io 3841, x 65, L = 0-79 

Jue, 2 Left valve, male, lo 3844, x 65, L = 0-88 

Fic. 3 Left valve, female, lo 3840, x 65, L = 0:88 

Fie. 4 Hinge of lo 3844, x 125 

Fie. 5 Central muscle scars of Io 3844, x 250 

Fic. 6 Left valve, female, lo 3839, x 65, L = 0-80 

LEE 7 Right valve, male, Ilo 3842, x 65, L = 0°83 

Fic. 3 Anterior tooth and hinge bar of Io 3844, x 650 

BIG. 9 Left valve, female, lo 3843, L = 0-93. Post-maturation moult stage. 
o) 


Fic. 1 Detail of pitting of Io 3839, x 750. 


Bull. Br. Mus. nat. Hist. (Geol.) 21, 6 PLATE 7 


Specimens of Fic. 1, 2, 4 from the Couches du Phare, Biarritz; specimen of remaining 


Pi AEs 


Cytheretta oligocaenica sp. nov. 


Fic. from Faluns Bleues. St. Geours-de-Maremne. 


Fic. 
Fic. 
Fic. 
Fic. 
Fic. 
Fic. 
Fic. 
Fic. 
Fic. 
Fic. 
Fic. 
Fie. 
Fic. 
Jae, 


MONI ANN WN H 


No} 


Left valve, female, Io 3845, x 70, L = 0-85, HOLOTYPE 


Carapace, dorsal view, male, Io 3847, x 70, L = 0-86 
Central muscle scars of lo 3849 

Right valve, female, lo 3846, x 70, L = 0-84 

Right valve, female, Io 3849, x 100, L = 0:84 
Right valve, female, Ilo 3849, x 100, L = 0-84 
Hinge of Io 3849, x 125 

Io 3849, x 70 

Anterior tooth of Io 3849, from dorsal, x 350 
Anterior tooth of Io 3849, from anterior, x 350 
Anterior tooth of Io 3849, from lateral view, x 350 
Posterior tooth of Ilo 3849, from ventral, x 350 
Posterior tooth of Io 3849, from posterior, x 350 
Posterior tooth of Io 3849, from lateral view, x 350. 


PLATE 8 


Bull. By. Mus. nat. Hist. (Geol.) 21, 6 


PLATE 9 
Alyx 70 


Fic. 1-4,6,7 Cytheretta cellulosa sp. nov. 


Fic. 
Fic. 
Fic. 
Fic. 
Fic. 
Jae. 


Fic 


Fic. 
Fig. 
Fic. 
Fic. 
Fic. 


18ne, 


Fic. 2 from Sables de Beauchamp, Moiselles; remainder from Sables d’Auvers- 
en-Oise. 


N OF WN H 


Left valve, female, lo 3859, L = 0:78; HOLOTYPE 
Right valve, female, Io 3860, L = 0-74 

Left valve, male, Io 3861, L = 0:96 

Male carapace, dorsal view, Io 3863, L = 0:93 
Right valve, male, lo 3862, L = 0:93 

Posterior view of Io 3863. 


. 5, 8, 9-11 Cytheretta carita sp. nov. 


Specimens from the Sables de Beauchamp, Moiselles. 


H 
HOW) CON 


lal 


12 


Female carapace, dorsal view, L = 0-87; specimen destroyed 
Female carapace, anterior view; specimen destroyed 

Left valve, female, Io 3853, L = 0-89; HOLOTYPE 

Right valve, female, lo 3854, L = 0-85 

Left valve, male, Io 3855, L = 0:94 


Cytheretta sp. B 
Right valve, Io 4093; Marnes a Pentacrinus, Biarritz. 


Bull. By. Mus. nat. Hist. (Geol.) 21, 6 PLATE 9 


Fic. 
Fie. 
Fic. 


Fic 


Fic. 
Fic. 
Fia. 
Fic. 


Fic. 


Fic. 


I 


3 
5 


PEATE ro 
* 7) 
Cytheretta geoursenis sp. nov. 
Specimens from the Faluns bleues, St. Geours-de-Maremne. 


Left valve, male, Io 3852, x 70, L = 1:07 
Left valve, female, Ilo 3850, x 60, L = 0:98; HOLOTYPE 
Right valve, female, lo 3851, x 70, L = 0-93 


. 2, 4, 6, 8, 9, Cytheretta laticosta (Reuss) 


aoanr N 


Specimens from the Middle Barton Beds, Barton. 


Left valve, female, lo 3865, x 70, L = 0-77 

Left valve, male, Io 3864, x 70, L = 0:90 

Right valve, male, Io 3866, x 70, L = 0-go 

Enlargement of Io 3864, central area between ventral and medium ridges, 
showing punctation. x 250. 

Further enlargement of Io 3864, showing a normal pore canal and sur- 
rounding puncta. x 850. 


Cytheretta carita sp. nov. 
Male carapace, ventral view, Io 3858, x 70, L = 0-93; Sables de Beau- 
champ, Moiselles. 


Bull. By. Mus. nat. Hist. (Geol.) 21, 6 PLATE to 


PATE ime 


x 70, except Fic. 7 


Fic. 1-4, 8,9 Cytheretta forticosta sp. nov. 


Fic. 1-4 from Upper Bracklesham Beds, Whitecliff Bay 


Fic. 
Fig. 
Fic. 
Fic. 
Fic. 


Fic. 


Fic. 


Fic. 
Fic. 


Fic. 


Con W NH 


Left valve, female, Io 3871, L = 0-79; HOLOTYPE 

Left valve, male, Ilo 3872, L = 0:87 

Right valve, female, lo 3874, L = 0:84 

Right valve, male, Io 3873, L = o-g1 

Female carapace, ventral view, Io 3875, L = 0.80; Upper Bracklesham Beds, 


Selsey. 
Male carapace, dorsal view, Io 3876, L = 0-92; Upper Bracklesham Beds, 


Selsey. 


Cytheretta porosacosta sp. nov. 


Left valve, male, Io 3880, L = 0-79 Middle Headon Beds, Colwell Bay. e 
Left valve, female, Ilo 3879, L = 0-75. HOLOTYPE; Middle Headon Beds, 


Colwell Bay. 
Enlargement of Io 3880 showing punctation x 140. 


Bull. Br. Mus. nat. Hist. (Geol.) 21, 6 PLATE 11 


PAD E, 12 


Fic. 1-2, 5 Cytheretta laticosta (Reuss) 


Fic. 
Fia. 
Fic. 


Fic. 


Specimens from Middle Barton Beds, Barton; x 7o. 


Male carapace, ventral view; Io 3869, L = 0-88 
Female carapace, dorsal view, Io 3868, L = 0:77 
Left valve, female, Io 3869, L = 0-81 


Cytheretta porosacosta sp. nov. 
x 70 


Right valve, male, Io 3882, L = 0-81; Middle Headon Beds, Milford. 
Right valve, female, Io 3881, L = 0-76; Middle Headon Beds, Milford. 


Cytheretta forticosta sp. nov. 


Right valve, female, lo 3878, x 70, L = 0:86; Upper Bracklesham Beds, 
Selsey. 

Dorsal muscle scars, x 350 

Posterior duplicature, x 350 

Anterior tooth, x 350 

Posterior tooth, dorsal view, x 350 

Anterior tooth, dorsal view, x 350 

Central muscle scars, x 350. 


Bull. By. Mus. nat. Hist. (Geol.) 21, 6 PLATE 12 


IPI INADIS, 03} 


Cytheretta tenuistriata ornata subsp. nov. 


Fic. 
Fic. 
Fic. 
Fie. 
Fia. 
Fic. 
Eee 
Fic. 
Fia. 


I 
2 
3 
4 
5 
6 
i 
8 


Ne} 


Fic. 10 
awe, iit 
1G, U2 


Left valve, female, Io 3898, L = 1:03, x 50; HOLOTYPE 
Right valve, male, lo 4021, L = 1:14, x 50 

Right valve, female, Io 3899, L = 1-02 

Left valve, female; specimen destroyed 

Left valve, male, Io 4020, L = 1°15 

Right valve, male; specimen destroyed 

Left valve, 8th moult stage, L = 0-87; specimen destroyed 
Right valve, 8th moult stage, Io 4025, L = 0-86 

Left valve, 7th moult stage, L = 75:; specimen destroyed 
Right valve, 7th moult stage, Io 4026, L = 0-80 

Left valve, 6th moult stage, Io 4024, L = 0°58 

Right valve, 6th moult stage, lo 4027, L = 0°59 


Specimens from the Falun d’Auvers-St.-Georges. 


Bull. By. Mus. nat. Hist. (Geol.) 21, 6 PLATE 13 


~ SENS ay 


OR ee 


PL AME: oa 
Cytheretta tenuipunctata absoluta subsp. nov. 


Fic. 1-4, 6, 7; x 60; specimens from the Marnes a Huitres, Cormeilles. 
KE, Left valve, female, Ilo 3884, L = 0:84; HOLOTYPE 


IRC, 2 Left valve, male, Io 3886, L = 0:98 

FIG. 3 Right valve, female, lo 3885, L = 0-87 

Fic. 4 Right valve, male, lo 3887, L = 0-98 

BiG, © Female carapace, dorsal view, Ilo 3888, L = 0-90 
Fic. 7 Male carapace, ventral view, Io 3889, L = 0-98. 


Cytheretta tenuipunctata lirata subsp. nov. 


Fic. 5, 8-10, x 50; specimens from the Falun d’Auvers-St.-Georges. 
Fig. 5 Left valve, female, lo 3890, L = 0-90; HOLOTYPE 
ETGaaO Right valve, female, L = 0-90; specimen destroyed 

Fic. 9 Right valve, male, lo 3893, L = 1-o1 

Fic. I0 Left valve, male, Io 3892, L = 1:04. 


Bull. Br. Mus. nat. Hist. (Geol.) 21, 6 PLATE 14 


dedomtn oe 
= MRELOTE, We bo 


Te, 


PLATE 15 
x 60, except Fic. 9, x 50 
Cytheretta buttensis reticulata sp. nov., subsp. nov. 
Fic. 1-8, Specimens from Cormeilles. 


MORPHOTYPE A. 


Ie, 1 Left valve, female, Io 4032, L = 0-85, Marnes a Huitres; HOLOTYPE 

FIG. 2 Left valve, male, Io 4033, L = 0.97, Marnes a Huitres. 

Fic. 3 Right valve, female, Io 4038, L = 0-82, Couches de Sannois 

FIG. 4 Female carapace, dorsal view, Io 4034, L = 0-91, Marnes a Huitres 

Fig. 5 Male carapace, dorsal view, L = 0-95, Marnes a Huitres. Specimen 
destroyed. 

MORPHOTYPE B 

Fic. 6 Right valve, female, L = 0-83, Couches de Sannois, Io 4036 

FIG. 7 Left valve, female, Io 4037, L = 0-88, Couches de Sannois. 


MORPHOTYPE C 
lee, Right valve, male, lo 4035, L = 0-96, Couches de Sannois 


Cytheretta buttensis buttensis sp. nov. 
18K, 1© Left valve, male, Io 4031, L = 0-91, MORPHOTYPE C, Couches de 
Sannois; HOLOTYPE 


Cytheretta tenuipunctata lirata subsp. nov. 
Fig. 9 Right valve, female, L = 0-90; specimen destroyed. 


Bull. Br. Mus. nat. Hist. (Geol.) 21, 6 PLATE 15 


PAPAS 16 


Cytheretta minipunctata sp. nov. 

FIG. I-3, x 50. Specimens from the Couches de Sannois, Cormeilles 
Fic. I Left valve, male, Io 4028, L = 1-10. HOLOTYPE 
rem Male carapace, ventral view, Io 4028 

Fic. 3 Female carapace, ventral view, lo 4029, L = 0:08. 


Cytheretta tenuipunctata lirata subsp. nov. 
Fic. 4 Left valve, male, lo 3894, L = 1:04, x 55; Falun d’Auvers-St.-Georges. 


Cytheretta tenuistriata tenuistriata (Reuss). 

Fic. 5,7 Specimens from the Unterer Meeresand, Alzey Trift 
FIG. 5 Left valve, male, lo 3896, L = 1:25, x 40 

FIG. 7 Right valve, female, Io 3897, L = I-10, x 50. 


Cytheretta minor (Lienenklaus). 
Fic. 6 Left valve, female, Io 3704, L = 0-88; Unt. Meeresand, Alzey Trift, x 60. 


Cytheretta aff. stigmosa Triebel. 
Fic. 8 Left valve, female, Io 4052, L = 0:76, x 65; Mid. Headon Beds, White- 
cliff Bay. 


Cytheretta gibberis sp. nov. 

Fic. 9, 10, x 70 Specimens from the Couches du Phare, Biarritz 
Fig, “9 Right valve, male, Io 4086, L = 0-92 

Fic. 10 Right valve, female, Io 4084, L = 0-88; HOLOTYPE. 


Bull. By. Mus. nat. Hist. (Geol.) 21, 6 PLATE 16 


’ ae ae = z. 
yee tome ‘ ‘x 


Sh A 


ae ee We 
face Ome ek 


PLATE 17 


Cytheretta stigmosa gallica subsp. nov. 

Fic. 1, 2, 10 Specimens from the Falun d’Auvers-St.-Georges, x 60 
Fic. I Left valve, female, lo 4053, L = 0-75; HOLOTYPE 

Fie. 2 Left valve, male, Io 4055, L = 0°73 

Bie. 5 Female carapace, dorsal view, L = 0-73; specimen destroyed 
EIG. 10 Male carapace, dorsal view, Io 4056, L = 0-74. 


Cytheretta regularis sp. nov. 

Fic. 3, 4, 5, 6, 7 Specimens from the Stampian of Gaas (Lesbarritz), x 60 
BiG Left valve, female, lo 4057, L = 0-70; HOLOTYPE 

Big. 4 Right valve, female, Io 4058, L = 0:68 

Ime, © Left valve, male, Io 4059, L = 0-70 

Fig. 7 Right valve, male, lo 4060, L = 0-68. 


Cytheretta vesca sp. nov. 

Fic. 8, 9, 12 Specimens from the Falun d’Auvers-St.-Georges, x 60 
Fic. 8 Left valve, female, lo 4048, L = 0:73; HOLOTYPE 
Fic. 9 Right valve, male, Io 4051, L = 0-71 

Fic. 12 Right valve, female, lo 4049, L = 0-72. 


Cytheretta headonensis Haskins. 

Fic. 11, 13, 14 Specimens from the Middle Headon Beds, x 50 
Fig. 11 Right valve, male, Ilo 4044, L = 0-80; Milford 

Fic. 13 Left valve, male, Io 4043, L = 0-78; Headon Hill 
Fig. 14 Right valve, female, lo 4046, L = 0:80; Headon Hill. 


Bull. By. Mus. nat. Hist. (Geol.) 21, 6 PLATE 17 


me 3 Dd 
I, oo gOee TF 


PREAH 2s 


Cytheretta posticalis parisiensis subsp. nov. 
Fic. 1-4, 6 Specimens from the Falun d’Auvers-St.-Georges 
Fie. I Left valve, female, Io 4039, L = 0:95, x 50; HOLOTYPE 


BiG. 2 Left valve, male, Io 4041, L = 1-05, x 50 

FiG. 3 Right valve, female, lo 4040, L = 0-91, x 50 

Fic. 4 Right valve, male, lo 4042, L = 1-03, x 50 

Fia. 6 Anterior radial pore canals of left valve, lo 3702, x IIo. 


Cytheretta bullans sp. nov. 

Fic. 5, 7, x 70 Specimens from the Calcaire a Algues, Blaignan 
Fic. 5 Left valve, female, Ilo 4061, L = 0:85; HOLOTYPE 
FIG. 7 Right valve, male, Io 4062, L = o-go. 


Cytheretta rhenana Triebel. 
Fic. 8 Left valve, female, lo 4047, L = 0°87, x 60; Unt. Meeresand, Alzey Trift. 


Cytheretta headonensis Haskins. 
Fic. 9 Left valve, female, lo 4045, L = 0:83, x 70; Mid. Headon Beds, Headon 
Hill. 


Bull. Br. Mus. nat. Hist. (Geol.) 21, 6 PLATE 18 


PLATE 19 


x 715 


Cytheretta sagri sagri Deltel. 
Fic. 1-4 Specimens from the Stampian of Gaas 


MORPHOTYPE A, Gaas (Espibos) 

le, 1 Left valve, female, Io 4063, L = 0:84 
Gee Right valve, male, Io 4066, L = 0-90 
Fig. 3 Right valve, female, Io 4064, L = 0°84. 


MORPHOTYPE D, Gaas (Lesbarritz) 
Fic. 4 Left valve, female, Io 4076, L = 0-92. 


Cytheretta sagri inconstans subsp. nov. 
Fic. 5-7, 9 Specimens from the Calcaire a Algues, Blaignan. 


MORPHOTYPE C 
Fic. 5 Left valve, male, lo 4069, L = 0-95 
le, © Left valve, female, lo 4070, L = 0:95. 


MORPHOTYPE B 
BG 7 Left valve, female, Io 4067, L = 0-78; HOLOTYPE 
Fie. 9 Female carapace, dorsal view, Io 4067. 


Cytheretta perita Deltel. 
Fic. 8 Left valve, female, lo 4089, L = 0-81; Bartonian of Le Vigneau. 


Cytheretta gibberis sp. nov. 
Fic. 10 Female carapace, dorsal view, Io 4085, L = 0:86; Couches du Phare, 
Biarritz. 


Bull. Br. Mus. nat. Hist. (Geol.) 21, 6 PLATE 19 


PLATE 20 


x 75 


Cytheretta sagri martini subsp. nov. 
Fic. 1-4 Specimens from the Couches du Phare, Biarritz 


MORPHOTYPE E 

Iie, it Left valve, female, Io 4071, L = 0-83; HOLOTYPE 
Fic. 2 Right valve, female, lo 4072, L = 0-81 

Fie. 3 Left valve, male, Io 4073, L = 0°86. 


MORPHOTYPE F 
Fic. 4 Left valve, male, lo 4074, L = 0-87. 


Cytheretta postornata sp. nov. 

Fic. 5-8 Specimens from the Couches de l’Atalaye, Biarritz 
Fie. 5 Left valve, male, Io 4088, L = 0-84 

IG, © Right valve, female, lo 4087, L = 0:83; HOLOTYPE 
Fic. 7 Right valve, male, lo 4088 

le, Left valve, female, lo 4087. 


Cytheretta sculpta Ducasse. 

Fic. 9, 10 Specimens from the Argiles a Algues, Blaignan 
Fic. 9 Right valve, male, Io 4o91, L = 0-73. 

Fic. 10 Left valve, female, lo 4090, L = 0-70. 


Bull. Br. Mus. nat. Hist. (Geol.) 21, 6 PLATE 20 


PLATE 22 
x 70, except Fig. 5 which is x 160 


Cytheretta minipustulosa sp. nov. 

Fic. 1-4 Specimens from the Couches du Phare, Biarritz 

lie, i Right valve, male, Io 4080, L = 1:09; HOLOTYPE 
IMG, 2 Right valve, female, Io 4082, L = 0-98 

EG 3 Male carapace, dorsal view, Io 4081, L = 1-00 

Fic. 4 Left valve, female, Io 4083, L = 0:88. 


Cytheretta samothracia Deltel. 

Fic. 5, 6, 8 Specimens from the Couches du Phare, Biarritz 
Fic. 5 Enlargement of the antero-dorsal area of Io 4077 
Ine, © Left valve, female, Io 4077, L = 0:95 

Fic. 8 Left valve, male, Io 4078, L = 1-04. 


Flexus lenijugum sp. nov. 

Fic. 7,9 Specimens from the Argiles a Algues, Blaignan 

HG. 7 Left valve, male, Io 4114, L = 0-80 

ne, & Right valve, female, lo 4113, L = 0:80; HOLOTYPE. 


Bull. By. Mus. nat. Hist. (Geol.) 21, 6 PLATE 21 


PLATE 22 
x 60 


Flexus plicatus (von Munster). 
BiG. 1 Left valve, Io 4094, L = 0-80; Chattian, Astrup. 


Flexus concinnus (Triebel). 

Ie, 2, 3} 

Fig. 2 Left valve, male, Io 4095, L = 0:94; Unt. Meeresand, Alzey Trift 
Fic. 3 Left valve, male, Io 4096, L = 0-81; Falun d’Auvers-St.-Georges 


Flexus sp. A 
Fic. 5 Left valve, female, Io 4118, L = 0-71; Sables de Lede, Bambrugge. 


Flexus gutzwilleri (Oertli). 
Fic. 4 Left valve, female, Io 4098, L = 0-79; Couches du Phare, Biarritz. 


Flexus schoelleri (Keij). 

Fic. 6-8 Specimens from the Faluns bleues, St. Geours-de-Maremne 
Fic. 6 Left valve, female, Io 4115, L = 0-71 

Fic. 7 Left valve, male, lo 4117, L = 0-74 

Fic. 8 Right valve, female, Io 4116, L = 0-71. 


Flexus lenijugum sp. nov. 

Fic. 9, 10 Specimens from the Argiles a Algues, Blaignan 

Fic. 9 Male carapace, dorsal view, lo 4114, L = 0-80 

Fic. 10 Female carapace, dorsal view, Io 4113, L = 0:80; HOLOTYPE 


Cytheretta bullans sp. nov. 
Fic. 11 Female carapace, dorsal view, Io 4061, L = 0-85; HOLOTYPE. Calcaire a 
Algues, Blaignan. 


Cytheretta postornata sp. nov. 
ETG. £2 Female carapace, dorsal view, Io 4087, L = 0-83; HOLOTYPE. Couches 
de l’Atalaye, Biarritz. 


Bull. By. Mus. nat. Hist. (Geol.) 21, 6 PLATE 22 


JPIGPNIPIS, 2S 


x 70 


Flexus ludensis sp. nov. 
Fic. 1-6, 16 Specimens from the Marnes a P. ludensis, Verzy, except Fig. 6 


Fic. 
Tes 
Fic. 
Fic. 
Fic. 
Fic. 
Fic. 


Left valve, female, Io 4106, L = 0:50; HOLOTYPE 

Left valve, male, Io 4107, L = 0-52 

Right valve, male, Io 4111, L = 0°51 

Male carapace, ventral view, Io 4109, L = 0:52 

Right valve, female, Io 4110, L = 0:51 

Left valve, male, Io 4112, L = 0-55; Mid. Headon Beds, Whitecliff Bay 
Female carapace, dorsal view, Io 4108, L = 0-50. 


Flexus solentensis solentensis sp. nov. 
Fic. 7-10 Specimens from the Middle Barton Beds 


Fic. 
Fic. 
Fic. 
Fic. 


7 
8 


9 
10 


Female carapace, dorsal view, Ilo 4101, L = 0-54; Alum Bay 
Left valve, Io 4101 

Right valve, female, L = 0:51; Barton; specimen destroyed 
Left valve, male, Io 4100, L = 0:54; Barton; HOLOTYPE. 


Flexus solentensis congestus subsp. nov. 
II-I5 Specimens from the Upper Barton Beds, Barton 


Rie: 
Fic. 
Fic. 
Fie. 
Fia. 
Fic. 


It 
1i7} 
13 
14 
15 


Left valve, female, Io 4103, L = 0-51; HOLOTYPE 
Male carapace, ventral view, Io 4104, L = 0°54 

Left value, Io 4104 

Right valve, female, Io 4105, L = 0-51 

Male carapace, anterior view, Io 4104. 


Bull, Br. Mus. nat. Hist. (Geol.) 21, 6 PLATE 23 


ee 
= - © 7 | vy 
: : am wy. is ia 7 _ =. 
ae oe 
5 


age «2, 
£ 


& 


\i 


Sle 


| 
_ 


4 


A LIST OF SUPPLEMENTS 
TO THE GEOLOGICAL SERIES 
OF THE BULLETIN OF 
THE BRITISH MUSEUM (NATURAL HISTORY) 


. Cox, L. R. Jurassic Bivalvia and Gastropoda from Tanganyika and Kenya. 
Pp. 213; 30 Plates; 2 Text-figures. 1965. 6. 

. Et-NaceGar, Z. R. Stratigraphy and Planktonic Foraminifera of the Upper 
Cretaceous—Lower Tertiary Succession in the Esna-Idfu Region, Nile Valley, 
Egypt, U.A.R. Pp. 291; 23 Plates; 18 Text-figures. 1966. {10. 

. Davey, R. J., Downtz, C., SARGEANT, W. A. S. & Witiiams, G. L. Studies on 
Mesozoic and Cainozoic Dinoflagellate Cysts. Pp. 248; 28 Plates; 64 Text- 
figures. 1966. £7. 

. APPENDIX. DAVEY, R. J., Downie, C., SARGEANT, W. A. S. & WILLIAMS, G. L. 
Appendix to Studies on Mesozoic and Cainozoic Dinoflagellate Cysts. Pp. 24. 
1969. 8op. 

. Ertiott, G. F. Permian to Palaeocene Calcareous Algae (Dasycladaceae) of the 
Middle East. Pp. 111; 24 Plates; 17 Text-figures. 1968. £5.12}. 

. Ruoves, F. H. T., Austin, R. L. & Druce, E. C. British Avonian (Carboni- 
ferous) Conodont faunas, and their value in local and continental correlation. 
Pp. 315; 31 Plates; 92 Text-figures. 1969. {TII. 


. Cuitps, A. Upper Jurassic Rhynchonellid Brachiopods from Noveinatatens : 


Europe. Pp. 119; 12 Plates; 40 Text-figures. 1969. £4.75. 


. Goopy, P. C. The relationships of certain Upper Cretaceous Teleosts with 


special reference to the Myctophorids. Pp. 255; 102 Text-figures. 1969. £6.50. 


ay 
. OWEN, H. G. Middle Albian Stratigraphy in the Paris Basin. Pp. 164; 


3 Plates; 52 Text-figures. 1971. 6. 


. Stippigul, Q. A. Early Tertiary Ostracoda of the family Trachyleberididae 


from West Pakistan. Pp. 98; 42 Plates; 7 Text-figures. 1971. £8. 


ae 
Bie Printed in England by Staples Printers Limited at their Kettering, Northants, establishment 


ee. 


INDEX TO VOLUME a1 


New taxonomic names and the page numbers of the principal references are printed in bold type. 

An asterisk (*) denotes a figure. 

References to ‘tab.’ without indication of a page number refer to no. 5 (Gitmez & Sarjeant): the tables 
follow p. 250. 


Acanthaulax 251 Aulacostephanoides mutabilis zone 177, 181 
venusta tab. 3, 5, 6 Aulacostephanus antissiodorensis zone 177-8, 
Acanthomorphitae 247-9 181, 184 
accessory septa 10 eudoxus zone 177, 181 
Acritarchs from Kimmeridgian 171-257 pseudomutabilis zone 177, 184 
incertae sedis 247-50 Auversian 267 
sp. indet. 250, tab. 4, 6; pl. 17, figs. 4 5 
Acuticytheretta 274, 276-7 Bachitherium 134, 141 
Adnatosphaeridiaceae 234-5 Bactrynium 5 
Adnatosphaeridium 234-5 Bairdia subvadiosa 284 
paucispinum 234-5, tab. 3, 5, 6; pl. ro, Baltisphaeridium 249 
figs. 1-4 claviculorum 248 
Aegivia 14 tnusitatum tab. 3, 5, 6 
grvayi 14, 25; pl. 4, fig. 3 barbets, see Capitonidae 
Aegivomena 3, 14, 20 Baryphthengus ruficapillus 163 
aquila 14, 25; pl. 1, fig. 3; pl. 3, fig. 5; pl. 4, baylet zone 175-7; see Pictonia baylei 
figs. 1-2 Belgium 264*, 266* 
Aegiromeninae 3, 12, 14-15, 17, 18*, 20; pl. 4 Belodinium dysculum tab. 3, 6 
Ahtiella 15 bema 10-11 
Airtonia 9 Bensonia 274, 276-7 
Alcedinidae 153-4, 161, 163-4, 166-8 knysnaensis 277 
Alcedo 159*, 163, 165*, 166 Biarritz 267 
atthis 153, 163 Billingsellacea 17, 19*, 23 
Aleodon brachyrhamphus 40 Billingsellidae 23 
alveolus Io Bilobia 15 
Ambocythere 274-5 Bimuria 12 
Amphitragulus 111, 113, 136 siphonata 12* 
anderidia 7, 9-10, 12, 20 Birgerbohlinia 138 
Andescynodon 39, 44 [footnote] Blastomerycidae 79, 133* 
Anopliidae 21 blastomerycines 134, 136 
Anoptambonites 12 Bohlinia 139 
Anseriformes 160 Bos 95 
Anticythereis euglypha 276 Boselaphini 125-7 
euglyphoidea 276 Boulonnais, Pas-de-Calais, Kimmeridgian 181-2 
Antilopini 127-31 Bovidae 125-31, 145-8 
Apteodinium 231-2 Bovini 125-7 
gvanulatum [no text] tab. 3-6; pl. 12, brachial ridges 1o 
figs. 4, 5 brachiopods, shell microstructure 4 
maculatum 231-2 morphology of shell 4-9 
cf. maculatum 231-2, tab. 3-6; pl. 12, fig. 6 brachiopore, ptycholophous 6 
Aquitaine Basin 264*, 266*, 267 Brachycythere 274 
Argenticythevetta 274, 277 Bracklesham beds 267 
Arhkellites hudlestoni zone 177 Bractypteracias leptosomus 166 
Aspatha gularis 163, 166 Bradleya 274 


Atelornis pittoides 164, 166 Bramatherium 138 


352 INDEX 


Brunton, C. H. C. 1-26 
Bucconidae 154, 163-4 
Bucerotidae 168 
Buntonia 274-7 


Cadomella 4, 19* 
Cadomellacea 4 
Cambridgeshire, Kimmeridge Clay 180 
distr. of microfossils in tab. 3 
Camelus 95 
Canningia minor 227 
vingnesit 227-8 
Cannosphaeropsis paucispina 234 
Canthumeryx 81, 82-4, 94, 136, 143, 145 
sirtensis 76, 81-4; pl. 1, figs. 2-5 
lower dentition 81-4 
Capitonidae 154, 162, 164, 167 
Capreolus 98, 101, 103, 105-6, 106*, 108, 110-3, 
I16—7, 119-22, 121* 
cavate cysts, indet.sp. A 245-6, tab. 4, 6; pl. 16, 
fig. 3 
sp. B 246, tab. 4, 6; pl. 16, figs. 2, 4 
Cervidae 131 
Cervoidea 78, 133* 
Charadriiformes 154, 160, 162-3 
Chiniquodontidae 30, 31*, 65 
Chonetacea 4, 9, 19*, 21, 25; pls. 1, 5-8 
ancestral stocks 9-13 
community on sea floor 22* 
lophophore 4 
morphology 4-9, 5* 
phylogenetic relationships with Plectam- 
bonitacea 18* 
shell structure 16-20 
spirolophe 4 
Chonetacean brachiopods, shell structure 1-26 
Chonetes (Eochonetes) celtica 16 
primigenius 15, 21 
Chonetidina 4 
chonetids 3-4, 18* 
Chonetoidea 3, 10, 15, 21 
Chonostrophia 9 
Chytroeisphaeridia 185-8, 251 
chytroeides 185-6, tab. 3-6; pl. 1, fig. 2 
euteiches 187 
mantelli 186-7, tab. 3-6; pl. 1, figs. 3-4; 
pl. 12, fig. 3 
pococki 187-8, 190-1, tab. 3-6; pl. 1, fig. 5 
sp. 187 
Ciconiiformes 160 
clavicular plates 11 
Cleistosphaeridium 235, 251 
ehvenbergi [no text] tab. 3-6; pl. ro, fig. 7 
machaerophorum 235 
polyacanthum tab. 3-6 
polytrichium tab. 3, 6 
tribuliferum tab. 3-6 
spp. 235, tab. 3-6; pl. 15, fig. 3 
Climacoceras 85, 131, 136 
Clitambonitacea 23 


Coccyzus 159* 
erythopthalamus pl. 3, fig. L 
Cooperina 5-6, 19* 
Coracias 159*, 163, 165* 
gavrulus 164, 166*, 167; pl. 3, fig. H 
Coraciidae 153-4, 162—4, 166-8; see Rollers 
Coraciiformes 153-4, 161-2, 163-4, 167-8 
Cormeilles-en-Parisis 265 
Cricodon 36, 37*, 39-40 
metabolus 40; pl. 3 
Crompton, A. W. 27-71 
Cryptarchaeodinium 191-3, 251 
calcavatum 191-2, 193, tab. 3, 6 [no fig.] 
cf. calcavatum 192*, 192-3, tab. 3, 6; pl. 2, 
fig. 3 
sp. tab. 5, 6 
Cuculidae 154, 161 
Cuculiformes 154, 162 
cusp nomenclature, ruminant molars and pre- 
molars 77*, 77-8 
Cylindrus jurinei 282 
Cynidiognathus 33*, 34 
Cynodontia [inford.] 30 
Cynodonts, postcanine occlusion in 27—71 
Cynognathidae 30, 31*, 65 
Cynognathus 34-5; zone 34 
Cynosauridae 30 
Cynosuchoides 34 
Cypridina laticosta 302 
plicata 339 
[cyst] organism A of Sarjeant, 1960 238 
Cythera multinervis 332 
Cythere 321 
costellata 289, 293, 295 
euglypha 276 
haimeana 295 
jurinet 296, 309, 311, 313 
tenuipunctata 309, 313 
plicata 304, 338-9 
laticosta 302 
Cythereis 268* 
euglyphoidea 276 
jurvinel 312, 320 
minor 319 
plicata 339 
vubya 275 
(Pseudocythereis) spinifera 275 
Cytherella 273 
calabra 284 
tenuistriata 312 
Cytheretta 262, 265, 267, 269-70, 272-7, 279*, 
280-1, 282, 283-338 
larval stages 280-1 
lineages, suggested, in NW Europe 268* 
soft parts 280 
type species 281-2 
valves, internal structure of 279* 
absoluta, see tenuipunctata 
adviatica 272, 284 
antecalva, see costellata 


INDEX 


bambruggensis 268*, 269, 271*, 293, 294, 
338; pl. 3, fig. 9 
belgica 272 
bernensis 268*, 307, 317-8 
bullans 263, 268*, 325-6, 327; pl. 18, 
figs. 5, 7; pl. 22, fig. 11 
buttensis 268*, 272, 315-6 
morphotype A 315, 317*; pl. 15, 
figs. I-5 
morphotype B 316, 317*; pl. 15, figs. 
Saal/ 
morphotype C 316, 317*; pl. 15, fig. 8 
buttensis 263, 307, 315, 316, 317*, 318, 
318*; pl. 15, fig. 10 
reticulata 263, 307, 316-7, 317*, 318*, 
332; pl. 15, figs. 1-8 
carita 262, 268*, 299-300, 300%, 345; pl. 9, 
figs. 5, 8-11; pl. 10, fig. 7 
cellulosa 262, 268*, 300-1, 345; pl. 9, figs. 
I-4, 6-7 
aff. cellulosa 301 
concinna 294, 339 
costellata 268*, 269-70, 272, 274, 278*, 
285-93, 286*, 291*, 293*, 345 
morphotype A 286*, 287, 292*; pl. 2, 


figs. 1-4, 6-10 

morphotype B 286*, 287, 292*; pl. 2, 
fig. 5 

morphotype C 286*, 287-8, 292*; pl. 3, 
fig. I 

morphotype D 286*, 288, 292*; pl. 3, 
figs. 3, 5 

morphotype E 286*, 288, 292*; pl. 3, 
figs. 2, 4, 6-8 

morphotype F 286*, 288, 292*; pl. 4, 
figs. 1-8 

morphotype G 286*, 288, 292*; pl. 4, 
figs. 9-11 : 


antecalva 263, 271*, 286*, 290%, 
291-3; pl. 4, figs. 9-11 
costellata 271*, 272, 286*, 289, 290*; 
pl. 2 
cratis 262, 271*, 278*, 286*, 290, 290*, 
292; pl. 4, figs. 1-8; pl. 5, figs. 1-3 
grandipora 262, 271*, 286*, 289-90, 
290*; pl. 3, figs. 1-8 
triangulata 287 
crassivenia 268*, 269, 271*, 293-4; pl. 6, 
figs. 2, 5 
crvatis, see costellata 
decipiens 268*, 269-72, 271*, 294; pl. 6, 
figs. 8-10 
aff. decipiens 271*, 294; pl. 6, fig. 3 
edwardsi 273, 280 
eocaenica 268*, 269-70, 272, 281, 296-7, 208, 
300-1; pl. 1, fig. 2 [no pl. caption]; pl. 7 
group 276, 345-6 
forticosta 263, 268*, 304, 305-7; pl. 11, 
figs. 1-4, 8-9; pl. 12, figs. 6-12 
gallica, see stigmosa 


353 


geoursensis 298-9; pl. ro, figs. 1, 3, 5 
gibberis 263, 268*, 332, 334-5; pl. 16, 
figs. 9-10; pl. 19, fig. 10 
gracilicosta 340 
gvandipora, see costellata 
grignonensis 268*, 269, 271* 
gutzwilleri 340; see Flexus 
haimeana 268*, 269-70, 271*, 294, 295, 296, 
345; pl. 6, figs. 1, 6 
group 276 
species-group, evolution of 270, 271* 
headonensis 268*, 270, 321*, 321-2, 345; 
pl. 17, figs. 11, 13-14; pl. 18, fig. 9 
inconstans, see sagri 
judaea 272, 281-2, 283*, 283-4; pl. 1, 
_ figs. 1, 4-7, 9 
jurinet 282, 296, 298 
Rlahni 268*, 321 
knysnaensis 273-4, 277; see Bensonia 
laticosta [superspecies] 269-70, 272, 302, 
303-7, 306*, 345 
[species] 268*, 302-3, 303*, 304-6; 
pl. 1, fig. 3 [me pl. caption]; pl. ro, 
figs. 2, 4, 6, 8-9; pl. 12, figs. 1-2, 5 
group 276 
livata, see tenuipunctata 
martini, see sagri 
minipunctata 263, 268*, 307, 314-5, 318; 
pl. 16, figs. 1-3 
minipustulosa 263, 268*, 332, 333-4, 333*; 
p. 21, figs. 1-4 
minor 268*, 301, 319, 325-7; pl. 16, fig. 6 
montensis 271*, 272; see nevua 
multicostata 268, 268*, 271* 
nevva 267, 268*, 269, 271*, 272 
montensis 268, 268*, 271*, 272 
oligocaenica 263, 268*, 269-70, 281, 
297-8, 299; pl. 8 
ornata, see tenuistriata 
parisiensis, see posticalis 
perita 268*, 332, 336-7; pl. 19, fig. 8 
plicata 339; see Flexus 
porosacosta 263, 268*, 304-7, 345; pl. 11, 
figs. 5-7; pl. 12, figs. 3, 4 
posticalis 268*, 319, 320, 332, 336-7 
parisiensis 263, 320-1; pl. 18, figs. 
I-4, 6 
posticalis 320, 321 
postornata 263, 268*, 332, 336, 337; pl. 20, 
figs. 5-8; pl. 22, fig. 12 
vamosa vamosa 307, 317-8 
sublaevis 307, 317-8 
regularis 263, 268*, 319, 325-6, 326*; 
pl. 17, figs. 3, 4, 6, 7 
reticulata, see buttensis 
vhenana 268*, 270, 300, 322-3, 325, 346; 
pl. 18, fig. 8 
headonensis 321 
stigmosa 323 
group 276 


354 INDEX 


vubya 275, 280-2, 283 
yuelensis 262, 268*, 271*, 295-6, 338; pl. 5, 
figs. 4-7; pl. 6, figs. 4, 7 
sagri 268*, 270, 272, 327-9, 332-4, 346 
morphotype A 328, 332; pl. 19, figs. 1-3 
morphotype B 328-9, 332; pl. 19, figs. 
729 
morphotype C 329, 332, 336; pl. 19, 
figs. 5, 6 
morphotype D 329, 332, 336; pl. 19, 
fig. 4 
morphotype E 329; pl. 20, figs. 1-3 
morphotype F 329, 336; pl. 20, fig. 4 
morphotype G 332 
inconstans 263, 330*, 330-1; pl. 19, 
figs. 5-7, 9 
martini 263, 330*, 331-2; pl. 20, figs. 
14 
sagyt 329-30, 330*, 331*; pl. 19, figs. 
1-4 
group 276 
sahnt 273 
samothracia 268*, 332-3, 334; pl. 21, figs. 
5, 6, 8 
schoellert 344; see Flexus 
scvobiculoplicata 268*, 269, 271*, 272, 294 
aff. scvobiculoplicata 271* 
sculpta 337; pl. 20, figs. 9, Io 
stigmosa 268*, 270, 318-9, 323, 325-7, 345 
gallica 263, 323-5, 324*, 326; pl. 17, 
figs. I, 2, 5, 10 
stigmosa 323 
aff. stigmosa stigmosa 270, 323; pl. 16, fig. 8 
sublaevis, see vamosa 
subvadiosa 281, 283, 284-5; pl. 1, fig. 8 
tenuipunctata [superspecies] 307-9, 309-17, 
318-9 
[species] 268*, 270, 272, 301, 309, 314, 
324, 332, 346 
absoluta 263, 307, 310-1, 311*, 312, 
318, 318*; pl. 14, figs. 1-4, 6-7 
lirata 263, 307, 310, 311-2, 318, 318%; 
pl. 14, figs. 5, 8-10; pl. 15, fig. 9; 


pl. 16, fig. 4 
tenuipunctata 307, 309, 310, 318* 
group 276 


tenuistviata 268*, 309, 312, 316, 318, 332 
ornata 307, 308*, 313-4, 314*, 320; 
pl. 13 
tenuistviata 307, 312-3, 318-9; pl. 16, 
figs. 5, 7 
tvacy1t 273, 280 
triebeli 268*, 307 
varviabilis 268*, 307, 318 
vesca 263, 268*, 322-3; pl. 17, figs. 8, 9, 12 
sp. A 296, 338; pl. 6, fig. 11 
sp. B 338; pl. 9, fig. 12 
sp. C 338; pl. 3, fig. 10 
Cytherettinae 263, 282-345 
characters of subfamily 277 


classification 274-7 
ecological distribution of Recent species 
272-3 

evolution of mid-Tertiary 270-2 
geographical distribution 274 
localities sampled for 266* 
mid-Tertiary of NW Europe 259-349 
palaeoecology 273-4 
shell structure 277—80 

Cytheridea stviatopunctata 282, 284 
subvadiosa 284 

Cytheridets colwellensis 321-2 

Cytherina costellata 289 
subradiosa 284 

Cytheromorpha 274 


Dacelo 159*, 161*, 163 
novaeguineae 163, 166*; pl. 3, fig. J 
Dama dama 81 
Davidsoniacea 4, 6, 19*, 23 
Daviesiella 9 
Daviesiellidae 9 
Dawsonelloides canadensis 17, 25; pl. 7, figs. 1-2 
Decennatherium 139 
Defiandrea 246 
Devonalosia wrightorum 26; pl. 8, fig. 4 
Diademodon 35-40, 37*, 39 [footnote], 48, 65*, 
67-8; pl. 2, fig. B 
Diademodontidae 30, 31*, 35-40, 44 [footnote], 
66 
postcanine teeth 37* 
Diarthrognathus 30 
Dicrocerus 85 
‘Dictyoclostus’ sp. 26; pl. 9, fig. 3 
Dictyopyxidia areolata 223 
Dictyopyxis 223-4, 251 
aveolata 223-4, tab. 3, 5, 6; pl. 7, fig. 9 
veticulata 224 
cf. veticulata 224, tab. 3, 5, 6; pl. 7, figs. 4, 5; 
Dire hes m2 
Sp. 223 
Dingodinium europaeum 244 
Dinoferophycidae 185-246 
Dinoflagellate cysts from Kimmeridgian 171-257 
Dinophyceae 185-246 
Dinophyciales 185-246 
cyst-family uncertain 233-4, 237-8 
Dorcatherium 79, 80, 139-40, 141 
chappuist 80, 139 
libiensis 76, 80; pl. 1, fig. 1 
naui 79-80 
parvum 140 
pigotti 80, 140 
songhorensis 140 
Dorset, distr. of microfossils in tab. 3 
Dremotheriidae 79, 133*, 137* 
Dremotherioidea 79 
Dremothevium 87, 89-91, 106, 111-3, 134, 136 
Dromomerycidae 79, 133* 
Dromomerycinae 131 


INDEX 355 


Dvinia prima 32, 33* 
Dviniidae 30, 32 
Dyoros 6-7 

sp. 6*, 8* 


East African ruminants 139-48 
Eathie Haven, Kimmeridge Clay 181, 182*, 183* 
Egmontodinium 228, 229-31, 251 
polyplacophorum 228, 229-31, 230*, tab. 
3, 6; plate 8; pl. 9, fig. 3; pl. 11, figs. 5, 6, 8 
Ellipsoidictyum 228 
aveolata 223 
endopuncta 7 
Endoscriniacea 239-40 
Endoscrinium 239-40, 251 
cf. campanula tab. 3, 5, © 
galeritum tab. 3, 5, © 
luridum 240, tab. 3-6 
oxfordianum tab. 3-6 
sp. 239*, 239-40, tab. 5-6; pl. 14, figs. 9-11 
Eochonetes 3, 10, 13, 21 
celtica 16 
primigenius 15 
Eomarginifera lobata 26; pl. 9, fig. 2 
Eoplectodonta 10-13, 13* 
tvansversalis 14, 25; pl. 1, fig. 4; pl. 2, 
figs. 4-6; pl. 3, figs. 1-4 
Eoplicanoplia 17 
Eotragus 127, 146, 148 
haplodon 127 
sansaniensis 127 
sp. 76, 127; pl. 13, fig. 1 (right) 
Eozostrodon 38, 68 
Eozostrodontidae 31* 
Epiplosphaera 251 
veticulospinosa tab. 3, 5, © 
Equus 95 
Etampes 266* 
Eucytheretta 274-5, 277, 338; see Flexus 
plicata 339 
Eumeryx culminis 134 
Europe, NW, mid-Tertiary Cytherettinae 259- 
349 
correlation of mid-Tertiary beds 264* 
Eurystomus 161*, 162-4 
glaucurus 164, 166*, 167 
Exaeretodon 44, 56, 58-60, 64, 65*, 67 
frengnelli 58, 59*, 60 


Falunia 281 
Flexus 262, 268*, 270, 272, 274-5, 277, 294, 
338-9, 339-46 
shell structure 281 
concinnus 270, 271*, 294, 339; pl. 22, figs. 
2,3 
congestus, see solentensis 
decipiens 270; see Cytheretta 
gvacilicostus 342 
gutzwilleri 271*, 340; pl. 22, fig. 4 
lenijugum 263, 343-4; pl. 21, figs. 7, 9; 
pl. 22, figs. 9, 10 


ludensis 262, 270, 342-3, 345; pl. 23, figs. 
I-6, 16 
plicatus 270, 271*, 275, 339, 344; pl. 22, 
fig. I 
schoellevi 344-5; pl. 22, figs. 6-8 
solentensis 270, 272, 340, 342-3 
congestus 263, 341-2; pl. 23, figs. 11-15 
solentensis 263, 340*, 340-1; pl. 23, 
figs. 7-10 
tviebeli 274 
sp. A 345; pl. 22, fig. 5 
foraminiferal shell linings tab. 3-5 
France, numerical distr. of microfossils in 
Kimmeridgian tab. 5 
Fregata 159*, 161*, 162 
ariel pl. 3, fig. B 
Fregatidae 154 
Fromea 188-9, 251 
amphora 188 
warlinghamensis 188-9, tab. 3, 4, 6; pl. 1, 
figs. 6, 8; pl. 9, figs. 5, 6 
Fromeacea 185-91 


Galbula leucogastra 164 
Galbulidae 154, 163-4, 167 
Galecranium 32 
Galeophrys 32 
Galesauridae 30, 31*, 32-5, 65 

postcanine teeth 33* 
Galesaurus 34 
Gazella 127-31 

capricornis 128-30 

gaudryi 128 

pilgvimi 128-30 

sp. 76, 126, 128-31; pl. 13, figs. 2, 3 

dentition, lower 128-9 
mandible 128 

Gebel Zelten, Libya 76-7 

Lower Miocene ruminants 73-150 
Geisleroceros 168 
Gelocidae 133*, 140-2 
Gelocus 140, 141 

communis 141 

whitworthi 76, 140-2; pl. 13, figs. 4, 5 
Geranopterus 168 
Givaffa 78, 86-8, 91, 95-101, 103, 105-6, 109-10, 

I13, 118, 118*, 122-4, 134-5, 139 
Giraffidae 75, 79, 85-103, 131, 137*, 138-9 
Giraffinae 75, 137*, 139 
Giraffoidea 75-150; 80-1, 131, 133*, 136 
giraffoids, effects of ossicones on evolution of 
134-6 

evolution of primitive 131-4 
Givaffokeryx 88, 91, 138 
GitMe£z, Mrs G. V. & SARJEANT, W. A. S. 171-257 
Glochinodon 34 
Glochinodontoides 34. 

gracilis 33*; pl. 2, fig. A 
gomphodont cynodonts 29-68 
Gomphodontosuchus 40, 44, 58-60, 64 


350 INDEX 


braziliensis 44, 54, 59-60 
Gonambonitacea 23 
Gonyaulacysta 193-214, 219, 231, 251 
? acevas 215 
aculeata tab. 3, 5, © 
amabilis 216 
angulosa tab. 3-6 
cauda 193-4, tab. 3, 5, 6; pl. 2, figs. I, 2, 4, 5 
cladophora [no text] tab. 3-6; pl. 2, figs. 7, 8 
ehrenbergit 205, tab. 4—6 
eisenacki [no text] tab. 3, 5, 6; pl. 3, figs. 6, 7 
evitti 220-1 
fetchamensis 205 
cf. giuseppei 194*, 194-5, tab. 4-6; pl. 3, 
figs. 3, 4 
globata 195-7, 196* tab. 3 4, 6; pl. 3, figs. 
Ui, 2 
granulata 251, tab. 3-6 
gvanuligeva 251, tab. 3-6 
helicoidea tab. 3, 5, © 
hyaloderma tab. 3, 5, © 
jurassica 251, tab. 3-6 
longicornis tab. 3-6 
longicornis 197-9, 198*, 251, tab. 3-6; pl. 2. 
fig. 6; pl. 4, fig. 1 
cf. mamiullifera 199-200, 201*, tab. 3-6; 
pl. 4, fig. 7 
nuciformis 197, 200-2, 201*, 251, tab. 3-6; 
pl. 3, fig. 5 
palla 205, 209 
perfovans 202-4, 203*, 212-3, 251, tab. 3, 4, 
6; pl. 4, fig. 6 
sevvata 207, tab. 3, 5, © 
systremmatos 204-5, tab. 5, 6; pl. 5, 
figs. 7, 8 
sp. A 205-6, tab. 3, 5, 6; pl. 9, figs. 1, 2 
sp. B 193, 206*, 206-7, tab. 4, 6; pl. 4, 
figs. 2, 3 
sp. C 204, 207-8, 207*, 209, tab. 4, 6; pl. 6, 
ED i, D 
sp. D 208-9, 208*, tab. 3, 6; pl. 6, figs. 4, 5 
sp. E 209-10, 210%, tab. 4, 6; pl. 6, fig. 9 
sp. F 211-2, 211*, tab. 3, 6; pl. 6, figs. 3, 6 
sp. G 212-3, 213*, tab. 3, 6; pl. 6, figs. 7, 8 
sp. H 213-4, 214*, tab. 3, 6; pl. 13, fig. 1 
Gonyaulacystacea 191-223 
Gonyaulax 216 
acevas 215 
amabilis 216 
longicoynis 197 
nuciformis 200 
perfovans 202-3 
Gravesia (gigas, gravesiana, ivius) zones 177 
Grekoffiana [‘Gvrekkofiana’] 274, 276-7; see 
Protocytheretta 
australis 276 
daniana 276 
Griquatherium 138 
Gruiformes 154 
gulls 153-4, 160 


Halcyonidae 153 
Halcyornis from Lower Eocene, affinities 151-69 
toliapicus 151-69, 155*, 156*, 157*, 158*, 
159*, 161*, 166*, 168; plates1, 2; pl. 3, fig. E 
cranium, compared with Recent forms 
157-63 
detailed comparison with coracii- 
formes and piciformes 163-7 
measurements 157 
state of preservation 154-7 
interorbital septum and foramen 160-2 
parasphenoid region 162-3 
orbit, upper edges of 159-60 
Halcyornithidae 153, 168 
Hamitton, W. R. 73-150 
Hampshire Basin 264*, 266*, 267 
Haplocytheridea 274 
Harrison, C. J. O. & WALKER, C. A. 151-169 
Headon beds 267 
Helaspis luma 26; pl. 9, fig. 1 
Helladotherium 138 
Hestertonia pellucida tab. 3, 5, 6 
Heterocemas 136 
simpsont 132-3 
Hexagonifera 240-1, 246, 251 
chlamydata 241 
jurassica 240-1, tab. 3-6; pl. 14, figs. 5, 8 
Sp. 240 
Hexagoniferacea 240-1 
Histiophora cf. ornata [no text] tab. 3-6; pl. 7, 
figs. 7, 8 
Honanotherium 137, 139 
horns, definition 78 
Horridonia horrida 26; pl. 9, fig. 4 
Hydaspitherium 138 
Hystrichosphaeridiacea 235-7 
Hystrichosphaeridium capitatum 189 
claviculorum 248 
petilum tab. 3-6 
pulchevrimum 235-6 


Ictidosauria 30, 31* 
Idoceras balderum bed 184. 
Ilyobates ? judaea 281-3 
Imbatodinium 232-3, 251 
antennatum 232-3, tab. 3-6; pl. 11, figs. 
2,3 
villosum 233 
cf. villosum 233, tab. 3, 6; pl. 11, fig. 1 
Sp. 232 
‘Indratherium’ 138 
inner side septum 10 
Inversella 15 
Ischignathus 60, 67 


Jura Mountains Kimmeridgian 184-5 
Juresania 17 


KEEN, M. C. 259-349 
Kenyameryx africanus 146 


INDEX 357 


Kimmeridge Clay microplankton 171-257 
zonal classifications 177 
Kimmeridgian microplankton, distribution com- 
pared with previously known stratigraphical 
range tab. 6 
Kingfishers, see Alcedinidae 
Kistecephalus zone 39 [footnote] 
Kuehneotheriidae 31* 


Lagomerycidae 131-2 
Lagomeryx 131-2 
simpsoni 132 
Lariidae 154, 160, 163, 167 
Lavus 159*, 165* 
argentatus pl. 3, fig. C 
canus 153 
vidibundus 153, 162 
toliapicus 153, 168 
Leavachia 33* 
durenhaget 32 
Ledian 267 
Leguminocythereis 274 
Le Havre, Kimmeridgian 183-4 
Leiosphaeridia (Chytroeisphaeridia) chytroeides 
185 
Leiostrea delta bed 190 
Leptaenisca 20 
Leptellinidae 13 
Leptelloidea 15 
leptelloides 25; pl. 5, fig. 3 
Leptestia 15 
musculosa 25; pl. 5, fig. 4 
Leptodinium 215-20, 251 
aceras 215-6, 215*, tab. 3, 4, 6; pl. 5, figs. 1-3 
amabilis 216-7, 217*, 220, tab. 3, 5, 6; pl. 10, 
figs. 5, 6 
arcuatum tab. 3-6 
clathvatum tab. 5, 6 
crassineyuum 219 
cf. crassinervum 218-9, 218*, tab. 3, 6; 
pl. 3, fig. 8; pl. 5, figs. 4-6 
egemenii [no text] tab. 3, 5, 6; pl. 7, figs. 1, 2 
subtile tab. 3, 5, © 
sp. 219-20, 220*, tab. 3, 4, 6; pl. 3, fig. 9 
Leptosomatidae 153-4, 162-4, 166 
Leptosomus 161*, 162-4 
discoloy 164-5, 166* 
Libya, Lower Miocene ruminants 73-150 
Libytherium 138 
Loculicytheretta 274 
London Basin 266* 
Lophiomeryx 134, 140-1 
lophophore 4-5, 7, 10-3 
lophophore platform 11 
Lorraine, Kimmeridgian 184 
Luangwa drysdalli 40 
Lucina inoynata, Marnes a 265 
Lystrosaurus zone 39 [footnote] 
Lyttoniacea 6, 19* 


Mainz Basin 266* 
Manda formation (M. Trias, Tanzania) 40, 43-4 
Massetognathus pascauli 56, 58-60 
Nn. sp. 44, 56-8, 57*, 60, 62*, 63-8, 65*; 
plate 7 
Megalaima 162-4 
haematocephala 164-5, 165* 
vivens 164, 165*, 166* 
Megathivis 7, 11 
Meiourogonyaulax 224-8, 251 
dicryptos 225-6, 225*, tab. 3, 5, 6; pl. 7, 
fig. 6 
pila 226-7, 227*, tab. 3, 4, 6; pl. 4, fig. 5; 
pl. 7, fig. 3 
staffinensis 224-5, 251, tab. 3-6; pl. 9, fig. 4 
sp. A tab. 3, 6 
sp. B 227-8, tab. 3, 4, 6; pl. 4, fig. 4; pl. 7, 
fig. 12 
Membranilarnax ovulum 223-4 
Meropidae 154, 163 
Merops 161*, 162-3 
apiaster 163, 166; pl. 3, fig. G 
Micrhystridium 247-8, 252 
fragile tab. 3-6 
inconspicuum 247-8, tab. 3-6 
vavispinum 248 
vecurvatum 247, tab. 3-6; pl. 17, figs. I, 2 
sydus tab. 3-6 
sp. 247-8, tab. 3, 6; pl. 17, figs. 7, 8 
Microdiniacea 223-31 
Micromeryx 144 
microplankton, organic-walled 171-257 
microstructure of brachiopod shell 4 
Mid-Tertiary beds of W. Europe, correlation 264* 
Miocene, Lower, ruminants of Libya 73-150 
Moiselles 265 
Momotidae 154, 161, 163-4, 166, 168 
Momotus 162-3, 165* 
martit 166* 
Monasa 162 
morphoeus 164-6, 166*; pl. 3, fig. I 
Mont Crussol (Rhone) Kimmeridgian 184 
Moorellina 7 
Morganucodon 38, 68 
motmots, see Momotidae 
Mudevorgia 241-2, 252 
mewhaet 242 
simplex 241-2, tab. 4, 6; pl. 15, figs. I, 2 
Mudevorgiacea 241-2 
muscles, mechanical advantage of, in Giraffidae 
101 
‘mutabilis’ zone 177 


Nanictosaurus 34 
Nanictosuchus 34 
Nannoceratopsis pellucida tab. 3, 6 
Nelsoniellacea 242-5 
Neochonetes 17 
Neocyprideis 274, 322 
colwellensis 322 


358 INDEX 


Neocytheretta 274-5 

Netrelytvon 251 
parum tab. 3-6 
stegastum tab. 3, 5, © 

Netvocytheridea 274 

Netromorphitae, organism A 249, tab. 3, 5, 6; 

plSn6; fies ipl aes 

nisusiids 17, 23 

Normandy, Kimmeridgian 182-3 

Ntawere Formation (Trias, Tanzania) 40 
(Zambia), undescribed cynodont reptile 

from 36 
Nucula comta, Argiles 4 (Belgium) 309, 339 


Occisucysta 220-3, 251 
balios 221; tab. 3-6 
evittt 220-1 [no fig. ] 
monoheuriskos 221-3, 222*, tab. 3, 6; 
pl. 7, figs. Io, 11 
RJD: AH), ison 3, ©) 
Okapia 78, 86-91, 95-101, 103, 105-7, 109-13, 
118-24, 118*, 119*, 120*, 121*, 134-5, 138 
oldhaminids (brachiopods) 4 
Oligocene, Upper 267 
Oligokyphus 67 
Oligosphaeridium 235-6 
pulcherrimum 235-6, 236*, tab. 3, 5, 6; 
plier igs 
Ovangiotherium 138 
Orthacea 23 
ossicones, definition 78 
effect on giraffoid evolution 134-6 
of Prolibytherium 107, 116 
pair of, indet. 85 
Ovis 118, 124 
outer side septum 10, 12 
Oxfordshire, Kimmeridge Clay 180 
distribution of microfossils in tab. 3 


Pachygenelus 30 
Palaeohypsodontus 131 
Palaeomerycidae 75-6, 78-9, 81, 82-5, 131-2, 
136-7, 137*, 142-5 
palaeomerycid, indet. 85; pl. 1, fig. 6 
Palaeomeryx 81-3, 92-5, 98, 105, 114, 121-2, 
131-4, 136, 141, 144-6, 148 
africanus 76, 131, 140, 143, 146 
furcatus 143 
MAgNUS 143 
sansaniensis 137 
sp. 84 
‘Palaeomeryx’ fold 77, 80-1, 84-5, 94, 128, 137, 
146, 148 
Palaeoperidinium bicuneatum 242 
nuciforyme 200 
nuciformoides 200 
veticulatum 224 
Palaeostomocystis laevigata 249 
Palaeotraginae 75, 85-103, 137*, 138-9 
Palaeotvagus 92-5, 98, 132, 137-9 


microdon 87, go-2 
vyouentt 94, 116 
Pavacytheretta 268*, 269, 274-5, 277 
veticosa 269 
schoelleri 344 
Paveodinia 251 
cevatophova tab. 3-6 
nuda 199 
Pareodiniacea 231-3 
Paris Basin 264*, 266* 
Parvocavatus tuberosus [no text] tab. 3-6; pl. 14, 
fig. 4 
Pascualgnathus 39, 44 [footnote] 
Pavlovia pallasianus zone 177 
pallasoides zone 177 
votunda zone 177-8, 180 
Pecora 134 
Pectinatites pectinatus zone 177-8, 180 
(Arkellites) hudlestont zone 177-8, 181 
(Virgatosphinctoides) elegans zone 177-8, 181 
scitulus zone 177-8, 181 
wheatleyensis zone 177-8, 181 
Pelecaniformes 154, 160, 162 
Pentacrinus, Couches a 338 
Pholadomya ludensis, Marnes a 264*, 265, 290, 
294, 299, 303, 342, 345 
Pholidostrophia 9 
Piciformes 153-4, 161-3, 164*, 167 
Pictonia baylei zone 177 
Platycraniellus 34 
Plectambonitacea 3, 9-13, 17, 19*, 20, 23, 25; 
plates 1-5 
phylogenetic relationships with Chonetacea 
18* 
shell structure 13-6 
Plectambonites seviceus 21 
Plectodonta 12-3 
Plurviarvalium 228 
Podocopida 282-345 
Podocopina 282-345 
pollen tab. 3-5 
Polymesoda 265 
Polystephanephorus 251 
savjeantit [no text] tab. 3, 5, 6; pl. 12, 
figs. 8, 9 
Pontocyprella 273 
Posidonia 272 
postcanine occlusion in cynodonts and tri- 
tylodontids 27—71 
Prionocytheretta 282 
Procellariidae 154 
Procellariiformes 154, 160, 162 
Procervulus 131, 136 
Procynosuchidae 30, 31*, 32-5, 39 [footnote], 65 
postcanine teeth 33* 
Procynosuchus 32 
Prodvemothevium 134, 141 
Productacea 4, 18*, 19, 19*, 23, 26; plate 9 
Productidina 4—6 
productids 4, 18* 


INDEX 359 


Proexaeretodon 60, 67 
Progivaffa 136 
Prolibytherium 84-5, 88-9, 104 
magniert 75-6, 104-25, 134-8, 137*; plates 
7-12 
astragalus 121-2, 125 
atlas 122, 123* 
brain 110-3, 112* 
calcaneum 121, 125 
cervical vertebrae 122, 123* 
dentition, upper 113-4, 116-7 
lower 114-7 
frontal 107 
functional interpretations 124 
humerus 118-9, 119*, 124 
jugal 106 
lacrymal 105-6 
mandible 113 
maxilla 105, 106* 
metacarpal 120, 125 
metatarsal 122 
occipital 108-9 
ossicones 107, 108* 
palatine 106 
parietal 107 
petrosal 110, 110* 
phalanges 122, 125 
post-cranial skeleton 117-25 
radius 119-20, 120*, 124-5 
scapula 118, 118*, 124 
skull 105-17 
sphenoid 109 
squamosal 109-10 
thoracic vertebrae 122-4, 123* 
tibia 120-1, 121*, 125 
ulna 120 
vertebral column 122-4 
Prolixosphaeridium 251 
cf. deivense tab. 3, 6 
granulosum [no text] tab. 3-6; pl. 13, figs. 
Om 
parvispinum tab. 3, 4, 6 
Propalaeoryx 81-4, 136, 142, 143-5 
austroafricanus 142 
nyanzae 76, 142-5; plate 14 
Protochonetes 15-6, 21 
ludloviensis 15, 17 
styiatellus 15-6 
Protocynodon 34 
Protocytheretta 273-7, 345 
damiana 273, 275-6, 345; see Grekoffiana 
multicarinata 273 
schoellevi 275, 344 
Protornis 168 
Protragocerus 126 
chantrei 126 
gluten 126 
sp. 76, 126, 127; pl. 13, fig. 1 (left) 
proximate cyst sp. indet. 233-4, tab. 3, 4, 6; 
pl. 11, figs. 4, 7,9 


Psaligonyaulax 251% 
apaleta tab. 3-6 
sp. tab. 3, 6 
Pseudocythereis 274-5, 277 
spinifera 275 
Pseudocytheretta 282 
pseudopuncta 7, 13-4, 16-7; plate 1 
Pteromorphitae 249-50 
Plevospermopsis 249-50 
australiensis [no text] tab. 3-6; pl. 12, 
fig. 7 
harti 249-50, tab. 3-6; pl. 17, fig. 6 
helios [no text] tab. 3, 5, 6; pl. 16, fig. 5 
Plterygocythereis 274 
Ptychoglyptus 15 
ptycholophe 5, 11 
ptycholophous brachiopore 6 
Puffinus 159*, 161* 
diomedia pl. 3, fig. C 
Purbeck, Isle of, Kimmeridgian 178, 179* 


Ramphastidae 154, 164, 166 
Rasenia (cymodoce, mutabilis) zones 177 
Retichonetes vicinus 17, 25; pl. t, fig. 2; pl. 7, fig. 3 
Rhactorhynchia inconstans bed 249 
Rhine, Germany 264*, 266* 
Rhinochetidae 154, 161 
rhynchonellids 13 
Rhynchops 160-1, 161* 
niger pl. 3, fig. F 
Rhynochetos 159* 
jubatus pl. 3, fig. A 
Richthofeniacea 6, 10, 19* 
rollers (birds) 153, 166-7; see Coraciidae 
Rugosochonetes silleest 17, 25; pl. I, fig. 1; pl. 7, 
fig. 4; pl. 8, figs. 1-3 
Spp. 17 
rugosochonetids 6 
Ruminants, Lower Miocene of Gebel Zelten, 
Libya 73-150 
East African 139-48 


Samotherium 98, 139 
sinense 87, 134 
SARJEANT, W. A. S. 171-257 
Scalenodon 36, 40, 41-56, 60 
angustifrons 40, 41, 42, 44 [footnote], 44-9, 
45*, 46*, 47*, 50-1, 53, 56, 58-60, 62*, 63, 
65*, 66-7; plate 4 
attridgei 29, 42, 43, 53-4, 55* (textfigs. 
10A, B) 58, 60, 63-4, 67; plate 6 
charigi 29, 42, 44, 54-6, 55* (textfig. 10C), 
60, 63-4 
hirschsoni 29, 42, 43, 49-53, 50*, 52*, 53* 
(textfigs. 7-9), 54, 58, 62* (textfig. 13), 
63-4, 65*, 67; plate 5 
Scalenodontoides 60 
macrodontes 59-60 
schizolophe 5, 11 
Scotland, distribution of microfossils in tab. 3 


360 INDEX 


Scriniodinium 242-4, 251 
bicuneatum 242-3, tab. 3-6; pl. 15, fig. 4 
cvystallinum tab. 3—6 
dictyotum 243-4 
dictyotum 243, 244*, tab. 3, 6; pl. 16, 
fig. 6 
osmingtonensis 243-4, 244*, tab. 3, 6; 
pl. 15, fig. 5 
papillatum 243-4, 244*, tab. 3-6; pl. 15, 
fig. 6 
pyrum 243-4, 244*, tab. 3, 5, 6; pl. 15, 
fig. 7 
cf. galeatum tab. 5, 6 
playfordi tab. 3-6 
Selenideva 162 
langsdorffi 164-5 
Semicytheretta 274, 276-7 
Sentolunia 10, 21 
Sericoidea 14-5, 21 
yestvicta 14, 25; pl. 4, fig. 4; pl. 5, figs. 1, 2 
shell structure, Chonetacean brachiopods 1-26 
side septa, inner and outer 10 
Silphedestes 34 
Silphedestidae 30 
Sivmiodinium 245, 252 
grossi 245, tab. 3, 6; pl. 16, figs. 7, 8 
Sivatheriidae 75, 79, 85, 103-25, 103-4, 137*, 
138 
Sivatherium 105, 109, 138 
Skye (Staffin Bay), Kimmeridge Clay 181 
socket ridges 11 
Solisphaeridium 248-9 
brevispinosum tab. 3, 5, 6 
claviculovrum 248-9, tab. 4, 6; pl. 17, figs. 
9, 10 
stimuliferum 252, tab. 3-6 
Sowerbyella 3, 13, 21 
(Viruella) liliifera 25; pl. 2 figs. 1-3 
Sowerbyellidae 9-10 12, 14, 18* 
Sowerbyellinae 12-4, 18*, 20; plate 2 
Spiniferites 251 
spores tab. 3-5 
Staffin Bay, Skye, Kimmeridge Clay 181 
Stampian 267 
Stapilinum cistum tab. 3, 5, © 
Stephanelytron 237-8, 251 
vedcliffense 237-8, tab. 5, 6; pl. 14, fig. 6 
cf. vedcliffense 238, tab. 5, 6; pl. 14, fig. 7 
cf. scarburghense tab. 3, 5, © 
Stevaspis zone 177 
Strophalosiacea 4, 6, 18*, 19, 19*, 26; plate 8 
stropheodontids 9 ~ 
Strvophochonetes 10, 15-6, 21 
celtica 16 
cingulatus 15 
primigenius 15-7, 25; pl. 5, figs. 5-8; pl. 6, 
figs. I-4 
Strophomenacea 4, 9-10, 18*, 19*, 23 
Strophomenida 4-5, 14 
phylogeny of superfamilies 19* 


strophomenids 3 
Subplanites (gvandis, wheatleyensis, spp.) zones 
177 
Sylvicapra 128 
Systematophora 237, 251 
aveolata tab. 3-6 
orbifeva [no text] tab. 3-6; pl. 13, fig. 2 
ovata 237, tab. 3, 6; pl. 14, figs. 1-3 
SP. 237 


Taeniophova 251 
tunctispina tab. 3, 5, 6 
taleolae 7, 13 
Tenua 187, 189-91, 251 
capitata 189, tab. 3-6; pl. 1, figs. 11, 12 
echinata 190, tab. 3-6; pl. 1, figs. 1, 9 
hystrix tab. 3-6 
pilosa tab. 3-6 
veyvucosa IQ 
villersense 191 
sp. 190-1, tab. 3, 6; pl. 1, figs. 7, 10 
tenuilobatus zone 177 
terebratulids 13 
Thaerodonta 13 
Thecideacea 4—6, 19*, 23 
Thecidellina 5, 11 
Thecospiva 4-5, 19* 
therapsid reptiles 30 
Thrinaxodon 33*, 34-5, 39 [footnote], 48, 65* 
liorhinus 34; plate 1 
Tinodon 38 
Toquimia 15 
Trachyleberidea 274 
Trachyleberididae 274, 282-345 
Tragulidae 79-81, 139-40 
Traguloidea 139-45 
Tvaversodon stahleckeri 54, 60 
Traversodontidae 30, 31*, 40-61, 65, 68 
distribution 60-1 
Tribolodon 34 
Triceromeryx 130-7 
Trichodinium sp. tab. 3, 6 
Triplesiacea 4, 23 
triplesiidines (brachiopods) 4 
Trivachodon 36, 39, 65* 
angustifrons 4% 
Trirachodontidae 30, 31*, 35-40, 39 [footnote], 
66 
postcanine teeth 37* 
Trithelodon 30 
Tritylodon 61-4, 62*, 65*, 67 
Tritylodontidae 31*, 61-4 
Tritylodontids, postcanine occlusion in 27-71 
Turdus sp. 167 


Uintornis 168 
Upupa 161*, 164 

epops 164-5; pl. 3, fig. K 
Upupidae 154, 161, 164, 166 


INDEX 361 


Veryhachium hyalodermum tab. 3-6 dentition, upper 90, 92-3 

Virgatites miatschkovensis zone 177 lower 90, 93-5 

Virgatosphinctoides (elegans, nodiferus, scitulus, ear region 89 

wheatleyensis) zones 177 femur 97, 102 
Viruella 13 frontal 87 
lihifera 25; pl. 2, figs. 1-3 functional interpretation ror, 103 

humerus 96, 102 
jugal 87 


Walangania 83, 141, 143-4, 145, 146-8 
africanus 76, 133, 141, 146-8 
dentition 147 
gracilis 76, 146 
WALKER, C. A. 151-69 
Warlingham (Surrey) borehole, Kimmeridge 
Clay 180-1 
numerical distribution of microfossils in 
Kimmeridgian tab. 4 
Weymouth district, Kimmeridgian 179*, 180 
wood fragments tab. 3-5 


lacrymal 87 

lumbar vertebrae 99*, 100-1 
mandible 89 

maxilla 86 

metacarpal 96—7, 102 
metatarsal 98, 103 

nasal 86-7 

occipital 87-8 

palatine 87 

parietal 87 

pectoral girdle 95 

pelvic limb 97-8 

phalanges 97, 102 
post-cranial material 95-103 
radius 96, 102 


Xenambonites 15 
Xestoleberis auvantia 321 


Zaphrentis delanouei 272 scapula 95-6, 102 
Zarafa 85, 105, 109-10, 114-6, 118, 118%, 120-2, skull 86-95 
I21*, 132, 134-6, 137*, 139 sphenoid 88 
zelteni 75—6, 86-103; plates 2-6 squamosal 88-9 
astragalus 98, 103 thoracic vertebrae 99*, 100 
axis 98-100, 99* tibia 97-8, 103 
calcaneum 98, 103 ulna 96 


cervical vertebrae 99*, 100 vertebrae 98-102, 99* 


il * x 
Oe by rote F y te < 
’ ti; he » 
" mt i 
, ‘ ' 
i © 
et ‘ ‘ 
; ( 
s 
P b 
a 
{ 
y,»' 
« 
+ 


Peay 


gy 


a * 4 ny 
or aa Ati 


=f ta : 


Senet nL 
Weeicegires trey ener 


383 


witty et 
Hints 
gesersatestezersesceass 
etzsete rere rereerers 


ceeregts 
Sorener satires